Arxiu d'etiquetes: dog

The problem of wild animals as pets

Although the first animals we think of as life partners are dogs or cats, the truth is that unfortunately many people decide to have a wild or exotic animal at home. Vietnamese pot-bellied pigs, sugar gliders, fennec foxes, meerkats, raccoons, monkeys… Is it possible to have a wild animal in good condition at home? What are the issues we can find? What wild mammals do people have as pets? We invite you to continue reading to find out.

WHAT IS THE DIFFERENCE BETWEEN A DOMESTIC ANIMAL AND A WILD ONE?

A domestic animal is an animal that has lived with humans for thousands of years. During the history of our species we have artificially selected these animals to obtain benefits, such as food, companionship or protection, like dogs, which have even co-evolved with us. Most domestic animals could not survive in the wild, as they would not know how to find food or would be easy prey for predators. Those who survive when abandoned, like some dogs or cats, cause serious problems to wildlife or even people.

 lobo perro dog wolf perro lobo
Some domestic animals, such as certain dog breeds (right), resemble their wild counterparts (wolf, left), which gives rise to the false idea that wild animals can be domesticated. Photo: unknown

And a wild animal? Many people confuse wild animal with ferocious or dangerous animal. A wild animal is an animal that has not been domesticated, that is, its species has not been in contact with people (at least not for thousands of years as the domestic ones). The fact that some wild animals are not dangerous (or not at all) for us, that they appear in series and movies, some celebrities own them and the desire to have a “special” animal at home, continues favoring the purchase-sale of these animals as pets.

monkey mono capuchino marcel ross friends
The character of Ross in the world-famous series ‘Friends’ had a capuchin monkey, which has to be donated when it reaches sexual maturity for aggressive behavior. Source

WHAT PROBLEMS DOES IMPLY TO HAVE A WILD ANIMAL AT HOME?

PROBLEMS FOR PEOPLE

The main reason why wild or exotic animals cause problems for humans is the lack of knowledge of the species: some have very specific diets that are practically impossible to reproduce in captivity. Others may live longer than the owner, be very noisy, occupy a lot of space, have nocturnal habits, transmit diseases or be poisonous. This results in maintenance difficulties and changes in  the behavior of the animal, until it becomes dangerous for its owner. The consequence is usually the abandonment of the animal, which will cause death, cause problems in nature or very high maintenance costs if they end up in a wildlife rescue center (according to Fundació Mona, keeping a chimpanzee costs 7,000 euros a year. Their life expectancy is 60 years: 420,000 euros in total for a single animal).

Raccoons undergo behavioral changes and may attack their owners. Source

Many species released in the wild end up being invasive, endangering the native ecosystems. If you want to know the difference between introduced and invasive species, read this post. To know the threats they pose to ecosystems, visit this post.

Do not forget that the purchase, sale and possession of many wild animals is totally illegal.

PROBLEMS FOR ANIMALS

Animals must live in an environment where their needs, both physical and mental, can be met. Although we put all our good intentions, give love and spend money keeping a wild animal, we  will never be able to reproduce their natural conditions. Lack of space, contact with other animals of their species, time searching for food, temperature conditions, humidity, light… the animal can not develop its normal behavior even if it is in the most optimal conditions of captivity.

The consequences that will suffer an animal that has not met their needs implies health problems (diseases, growth deficit…) and behavior (stereotypic-compulsive movements, self-injury, anxiety, aggression…).

A fennec fox, a carnivorous animal of the desert, in an evident state of illness. According to social networks, because he was being fed a vegan diet. According to its owner, Sonia Sae, because it is allergic to pollen despite following a vegan diet. Be that as it may, it is clear that the pollen amounts in Sahara have nothing to do with those of Europe. Source

Finally, the most serious consequence when we acquire a wild animal is that we are favoring the trafficking of animals, the death of thousands of them during transport to our house and even their extinction. Animal trafficking is the second cause of biodiversity loss on our planet, behind the destruction of habitats.

Slow loris are nocturnal and poisonous animals that are marketed as pets and, like mostof them, are transported under terrible conditions. Learn more about the calvary of slow lories visiting blognasua. Photo: Naturama

EXAMPLES OF WILD MAMMALS AS PETS

PRIMATES

Marmosets, slow loris, lar gibbons, chimpanzees, Barbary macaques… The list of primates that people have in captivity is almost infinite. One of the main mistakes people make when they want a primate as a pet is to believe that they have our same needs, especially in superior primates such as chimpanzees. Its expressions are also confused with ours: what the photo shows is not a smile of happiness and what the video shows is not tickling, but an attitude of defense (slow loris have poison in their elbows).

This chimpanzee is not smiling, he is scared. Photo: Photos.com

Many primates live in family groups and the offspring need to be with the mother the first years of life, so that just the simple fact of acquiring a little primate entails the death of all the adults of their family group and psychological problems for the animal. To know the extensive and serious problem of keeping primates in captivity, we strongly recommend reading this post.

SUGAR GLIDERS

Sugar gliders (Petaurus breviceps) resemble a squirrel, but in fact they are marsupials. They have a very specific diet (insects and their depositions, eucalyptus sap, nectar …), they live in the canopy of trees in groups from 6 to 10 individuals and move between the trees jumping up to 50 meters with a membrane that let them hover. They are nocturnal so they yell and call at night. It is evident that it is impossible to reproduce these conditions in captivity, so the majority of sugar gliders die due to nutritional deficiencies.

Sugar glider caged. Photo: FAADA

VIETNAMESE POT-BELLIED PIGS

Although they are a variety of a domestic animal, Vietnamese pot-bellied pigs (Sus scrofa domestica) are small when tey are young, but adults can weigh more than 100 kilos, so it is impossible to keep them in a flat. There have been so many abandonments and they have reproduced so much, that there are populations established in nature. They can reproduce with wild boars and it is unknown if the hybrids are fertile. There are no wildlife recovery centers or shelters for these pigs, so they continue to affect the native ecosystems.

Since actor George Clooney introduced a Vietnamese pot-bellied pig as a pet, the trend to own one quickly spread. Source

RACCOONS AND COATIS

Other mammals that, because of their pleasant appearance, some people try to have as pets. Raccoons (Procyon sp) develop aggressive behaviors when they do not having their needs covered, they are destructive to household objects and have a tendency to bite everything, including people. Currently in Spain and other countries it is illegal to acquire them and it is classified as an invasive species.

In addition to aggressiveness, one of the most common behaviors of raccoons is “theft”. Source

Coatis (Nasua sp) are related to raccoons and, like them, when they grow up they become aggressive if kept in captivity in a home. In Spain, their possession is also illegal.

coatí nasua
The coati, another friendly-looking mammal that can be dangerous. Source

MERKAATS

Merkaats (Suricata suricatta) are very social animals that live in colonies of up to 30 individuals underground in the South African savanna. They usually make holes in the ground to protect themselves and are very territorial. Therefore, having a meerkat at home or in a garden is totally unfeasible. In addition, the climatic conditions (high temperatures and low humidity) in which they are adapted are not the same as those of a private home.

As sugar gliders, their food is impossible to reproduce at home: snake meat, spiders, scorpions, insects, birds and small mammals… Like raccoons, they do not hesitate to bite and are very active animals.

Meerkat with a leash where you can see his fangs. Photo: FAADA

FENNEC FOX

This species of desert fox (Vulpes zerda) has also become trendy as a pet. Although its tenure is still legal, it has been proposed several times as an invasive species.

The main reason why you can not have a fennec at home are the desert climatic conditions to which it is adapted. Living in an apartment causes kidney problems and thermoregulation problems. Also, it is a nocturnal animal. Changes in their circadian rhythm cause them hormonal problems.

Fennec  fox in the desert. Photo: Cat Downie / Shutterstock

Like the previous two species, behavioral problems can turn up and become violent against the furniture or its owners.

ELEPHANTS, TIGERS …

Although it may seem incredible, there are people who have an elephant in the home garden and other people have felines, like tigers. At this point we do not think it is necessary to explain the reasons why these animals have not their needs met and the potential danger they pose to their owners and neighbors in case of escape.

Dumba, the elephant that lives in a home garden in Spain. Photo: FAADA

IN CONCLUSION

As we have seen, a wild animal in captivity will never have its needs covered to guarantee its welfare. Here we have presented the best known wild mammals that are kept as pets, but unfortunately the list does not stop expanding.

In order not to favor animal trafficking and cause unnecessary suffering during the life of the animal, avoid buying wild animals, inform yourself and inform the people around you, denounce irresponsible tenures and in case you already have one wild animal as a pet and you can no longer keep it, contact a recovery wildlife center and never abandon it into nature.

MIREIA QUEROL ALL YOU NEED IS BIOLOGY

 

DNA: the solution to combat the dog mess

You are walking quietly and suddenly you smell an unpleasant odour. You look from side to side and you see nothing, but the smell continues there. Then, you lift your foot and, effectively, you have stepped a dog poop. You cannot deny it because everybody has happened it. However, DNA can finish with the lack of public spirit. If you do not believe it, I suggest you to continue reading.

THE CONSEQUENCES OF THE LACK OF PUBLIC SPIRIT OF SOME DOG OWNERS

To have a dog is not only feed up it and play with it, but its owners are the person responsible to duck and clean the dog mess and deworming it. However, few people do it.

In the street, in playgrounds or in front of the home’s door you can find the dropping of a dog because its owner has not cleaned it. Although there are many campaigns against the lack of public spirit of some dog owners and there are also economic sanctions, today is an unresolved issue.

To leave dog droppings is not only an unsightly problem, but it goes beyond because parasitized stools are a public health issue. If the stools are not cleaned soon, eggs or cysts presents in them may become infectious forms and represent a risk to people or children who play in the playground. The rain dissipates the stools and people do not see them, but the parasites are still there.

Intestinal worms cause diseases to dogs and cats and people, especially in children and immunocompromised (HIV, transplant patients or with some types of cancer subjected to long immunocompromised therapies).

Parasites can cause health affect to stomach and intestines, but the worst is in the eyes. The parasite Toxacara canis can cause the total loss of vision of the eye that infects.

CAN-ID PROJECT

Oscar Ramírez is the person responsible of the Can-ID project (Figure 1), developed by the Catalan company Vetgenomics SL to combat stools in public spaces. This is a system of canine identification by DNA, based on a chip of 128 markers (SNPs).

logo_can-id_web
Figure 1. Logo of Can-ID (Source: Vetgenomics SL)

The aim of Can-ID is identify all dogs of a municipality with a chip to get a census of dogs. When a council’s technician finds a dog mess, he will pick up a sample and he will send it to analyse. Then, if the DNA removed of the sample coincides with the chip of some registered dog, it will know who the dog owner is. Finally, the council could fine this person.

This project is based on two phases:

Phase 1: genetic identification of all dogs of municipality

  • Involvement of vets in the collection of blood or saliva samples
  • Identification plate with QR code, which the owner can activate in case of loss of the dog
  • Transport with custody system of samples
  • Analysis of the samples and obtaining the genetic profiles
  • Creation, management and conservation of the database with the genetic profiles of dogs in the municipality

Phase 2: identification of owners with a lack of public spirit

  • Non civic owner does not pick up his dog’s stool from the street
  • Collection of samples in the presence of members of the local police
  • Transport with custody system of samples
  • Analysis of stool samples in a laboratory specialized in non-invasive samples
  • Comparison of the genetic profile of the stool with the database. Identification of the dog

In order to realize the first phase, the municipality has to modify the municipal ordinances so that, in addition to force the registration of the dogs and an identification by a chip, their owners also submit them to a blood test that will help to make a database.

Unlike what many people think, genetic identification has not a great cost. Moreover, the cost of cleaning the municipality is higher. The first phase has a cost of 35€ per sample and includes the extraction of a sample by a vet and its custody for analysis. The second phase is also around 30€ and the amount of the fine is around 300-600€, depending the city. Therefore, the municipalities that implement this system would recover the investment.

Parets del Vallès (Barcelona) is the first town to implement this system. In the first 3 months, the municipality pays for the collection of samples and their custody, through an awareness campaign.

WHY CHOOSE CAN-ID?

This system has a greater number of markers respect to other identification systems (Table 1), but it also has internal pollution controls.

This system allows to exclude the false positives. A dog may urinate on a stool in the street. This would contaminate the sample, but this system is able to identify if the sample contains more than one DNA. If so, the sample would be excluded.

It can also happen that the dog is not registered or is from another population. But you can obtain a robot portrait and put stronger pressure on dog owners who comply the characteristics of the robot portrait (example: hair colour).

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Table 1. Comparision of the Can-ID system respect others identification systems (Source: Oscar Ramírez, Comparative Genomics programme from Master’s Degree in Cytogenetics and Reproductive Biology in UAB)

In addition to identify these people, Can-ID can be applied for genetic identification and paternity tests or monitoring of wild-wolf populations from non-invasive samples too (stools, hair, urine).

We hope that more municipalities will join this initiative and reduce the lack of public spirit of some people, which may affect public health.

REFERENCES

mireiaramos-angles

The Iberian wolf: laws and conservation in Spain

The wolf is one of the most iconic carnivores, especially in Spain. However, an unwarranted bad reputation kills hundreds of individuals a year. Find out in this post more about this wonderful animal and the conservation efforts that are currently being made with the Iberian wolf.

HOW MANY WOLF SPECIES EXIST?

The classification of species and subspecies of the wolf is still unclear, although most authors consider that there are 7 species of wolf: gray wolf (Canis lupus), red wolf (Canis rufus), ethiopian wolf (Canis simensis), eastern wolf (Canis lycaon), golden jackal (Canis aureus), himalayan wolf (Canis himalayensis) and indian wolf (Canis indica). Although some features are common to all species, we will focus on the gray wolf and specifically in the subspecies iberian wolf (Canis lupus signatus).

canis, lupus, signatus, lobo, ibérico, llop, ibèric, wolf
Canis lupus signatus. Photo: Mireia Querol

THE WOLF

The wolf or gray wolf (Canis lupus) is the largest wild member of the family Canidae. It was the carnivore with the world’s largest area of distribution, but now it has been reduced drastically by human pressure. Canis lupus has about 32 subspecies and it is considered least concern in the IUCN red list globally, but locally it is listed as endangered. As we saw in a past post, the dog (C. lupus familiaris) is subspecies of the gray wolf .

mapa, distribución, lobo, canis lupus, map, dsitribution, distribució, llop
Wolf’s distribution (Canis lupus). Source: IUCN

SOCIAL ORGANIZATION AND HUNTING

Wolves are social animals: their survival and success as a predator depends on their organization in packs (8 to 12 members). The hierarchy within the pack is based on a breeding pair (usually a lifelong couple) and the other members cooperate in hunting and caring for the young.

In a pack, members maintain extensive territories by olfactory and acoustic tags. The howl of the wolf is used to announce their presence and defend territories. It can be heard up to 10 km away and allows rival packs stay away and avoid confrontations. It is also used to communicate and strengthen ties within the members and to express emotions.

Lobo aullando. Foto: UK Wolf Conservation Trust
Wolf howling. Photo: UK Wolf Conservation Trust

They are adapted to walk and run long distances in search of prey in a variety of terrains (forest, meadow, snow…) and are also good jumpers while running. Its great smell, good sight (diurnal and nocturnal thanks to the tapetum lucidum) and impressive teeth makes them effective predators. In addition, the group hunting allows them to kill prey up to 10 times its weight. Once it is tumbled, members wait their turn after the dominant pair has feed on it. In case of shortage of food, wolves can scavenge dead animals and even practice cannibalism.

bisonte, lobo, cazando, bison, wolf, hunting
Pack lurking a bison. Font

REPRODUCTION

From January to April, the dominant female gives birth to 4-7 cubs. After a month of breastfeeding, the cubs leave the burrow and feed on food regurgitated by their parents and other members of the group. If the food is abundant, after 3-5 months the cubs are ready to travel with the rest of the group. The next breeding season, some youth will abandon the pack searching for mates and territory.

THE IBERIAN WOLF

The Iberian wolf is found exclusively in the Iberian Peninsula. Its scientific name “signatus” refers to the signs in their fur that differentiate it from Eurasian wolf (Canis lupus lupus).

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Eurasian wolf (Canis lupus lupus). Photo: Quartl

 

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Iberian wolf’s fur (Canis lupus signatus). Source

The Iberian wolf packs has fewer individuals (up to 7 and often only a couple with a subadult) due to the smaller size of the prey and food availability (roe deers, sheeps, mountain sheeps, rabbits).

If you want to know more about the iberian wolf you can download the app iFelix (in spanish) listed here .

DISTRIBUTION AND ROLE OF THE WOLF IN THE ECOSYSTEM

In the early twentieth century the wolf was distributed throughout all the peninsula. It has now been restricted almost to the peninsular northwest and around 2,800 individuals in total exist. The year 2000 the wolf reappeared in Catalonia, which could give the impression that the Iberian wolf was expanding, although genetic analysis in a 2011 study showed that came from the Italian-French lineage and only 13 different individuals were identified.

Mapa de distribución del lobo ibérico. Fuente
Distribution map of the Iberian wolf. Source

Large predators are essential for the survival of biodiversity of ecosystems. The wolf is a key species in this role, because its influence is greater than other species. This is due to its ability to modify the density and performance of dams and its interactions with other species, as scavengers. An example is this viral video in which the presence of the wolf ultimately led to the modification of the river in Yellowstone:

THREATS OF IBERIAN WOLF

Iberian wolf threats are basically due to humans:

  • Increasing human pressure that invades their original habitats
  • Forest fires
  • Competition with farmers and hunters (economic interests, ignorance and superstitions)
  • Fragmentation of habitat due to highways and railways (which also cause collisions)
  • Disinterest of competent authorities
Corpses of wolves appeared in Asturias. Tensions between farmers and administrations have generated in recent months ghoulish images like these (Tiós, 2015). Various sources

LEGAL STATUS OF THE WOLF IN SPAIN

According to the Red Book of Vertebrates in Spain the wolf is listed as vulnerable. However, populations at north of the Duero River can be controlled hunted and beated in exceptional cases, even during the breeding season. Only the municipality of Muelas de los Caballeros wants to ban hunting considering the wolf as an “emblematic species”. In Portugal conservation is somewhat higher, but when wolves cross the border are hunted indiscriminately in Galicia and Zamora, disabling conservation efforts in the neighboring country.

By contrast, the populations of southern Duero are protected by the Habitats Directive of the EEC and by various laws of the Spanish state. However, in April 2016 the government suggested removing this protection, but it has not succeeded. So a river separates the wolves that can be hunted and prosecuted from those who are protected. But if you look at the distribution map, this protection at south of the Duero may be useless, because probably there are no remaining wolves in that area.

THE VARMINTS’ EXTINCTION JUNTAS

The Juntas de Extinción de Animales Dañinos existed in Spain between 1954 and 1968. Their goal: to offer economical rewards to kill species that were detrimental to hunting and livestock. In that period, 196,147 animals were killed (the numbers are probably higher than reported), including 1,470 wolves. Today there are still people who claim the return of the varmint killers.

Currently it is estimated that each year about 500 wolves die because of legal and illegal hunting, poisoning and vehicle collisions. The greatest enemy of the wolf is the atavistic fear and hatred aroused among people living with they, and the few or inexistence interest of administrations: they do not allocate enough money to offset the economic losses that the wolf may cause farmers.

ECONOMIC LOSSES IN LIVESTOCK

As we have seen, nearly 90% of the wolf population live in Castilla y Leon and Galicia. In Galicia they live in areas with high human density, which forces them to feed mainly on cattle and debris dump. There is a belief that wolves kill for killing, because they attack more sheep than they can feed. It is totally false that wolves kill for pleasure. According to some authors, this corresponds to an ancestral behaviour, not yet lost, to forecast food supplies for periods of scarcity. Others argue that responds to the fact that when the wolf is preparing for the hunting, enters into a state of tension and excitement necessary to bring down wild animals. But as sheep dont’ try to defend themselves or try to scape, the wolf releases this excitement the only way it knowns.

IN CONCLUSION

As the bear and lynx have different conservation plans, the wolf has none. Most regions with the presence of Iberian wolf have to subsidize farmers who suffer economic losses due to wolf. However, some offsets aren’t paid until four years later or they are not implemented at last, and the authorities do not meet the demands of farmers. By contrast, some farmers resort to fraud to take advantage of such compensations. Real conservation policies and the application of subsidies and penalties are necessary to ensure the survival of the Iberian wolf in Spain, an animal that is becoming depleted.

REFERENCES

How animals see the world?

Have you ever heard that dogs see in black and white? Or that cats can see in the dark? Why we have our eyes in front of the face? And why goats have an horizontal pupil? This article will answer these and other questions about the eyes and vision, focusing on mammals.

HOW IMAGES ARE FORMED?

The eyes are the receptors responsible for capturing light and sending the signal through the optic nerve to the brain, which make the interpretation. Light is an electromagnetic wave as infrared, ultraviolet, X rays, microwaves, etc. In this post we will refer to visible light, that is, the part of the spectrum that can perceive humans and most mammals.

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Parts of the eye. Source

Basically, the light passes through the pupil. It can regulate the amount of light thanks to the muscles associated with iris (which gives color to the eye). The lens focuses the objects. The image is projected inverted in the retina, to be sent as an electrical signal to the brain.

WHY DO WE SEE IN COLOR ?

In the retina there are two main types of photoreceptor cells: cons and rods. The main differences are:

RODS
  • More sensitive in a few light conditions
  • No color vision
  • Motion-sensitive
  • Less image detail
CONES
  • Activated under conditions of high light
  • Color vision
  • Contrast-sensitive
  • High image detail

That’s why in low light, vertebrates see in black and white and the image is not clear, since the rods are activated at maximum but the cones are inactive. Some primates have three different kinds of cones (trichromatic vision), which correspond to the red, green and blue colour (RGB). Some primates and other animals have monochromatic vision (they only have one type of cone) or dichromatic (two). Some animals have tetrachromic vision, like birds.

The cones are sensitive to different wavelengths, different colors. Photo taken from Colombian Primatological Association

Generalizing a lot, diurnal vertebrates have more cones than rods and nocturnal ones have more rods than cones, allowing them to see better in the dark. But they can really see in the dark?

SEEING IN THE DARK

In total absence of light it is impossible to see, although some animals can detect other radiation such as infrared (snakes) or ultraviolet (bees). In addition to the relation between rods and cones, other factors that improve vision in low light conditions are:

THE CORNEA

The bigger the eye and the cornea, the better use of light. The mammal with the greatest cornea in relation to the eye is the Philippine tarsier (Carlito syrichta ) a nightlife primate.

Philippines’ tarsier (photo: Yeo Kok Leng)

THE PUPIL

Another way to take advantadge of few light conditions is increasing the size of the pupil. According to the shape of it, the control of incoming light is more precise: it is the case of many cats. Compared with a round pupil, the elongated one opens and closes sideways and according to the position of the eyelid, pupil surface exposed to light can be controlled better.

The felines with vertical pupil can open it horizontally and control better the entry light than with a circular pupil. Image of an unknown author, adapted from Aquàrium-Liège Museum

 

THE TAPETUM LUCIDUM

Cats, dogs, bats, horses, whales, crocodiles, cattle and some nocturnal primates have in the retina or behind it a bright layer called tapetum lucidum, which increases up to 6 times the light gathering ability compared to humans. As if it were a mirror, the tapetum lucidum reflects the light reaching the eye to return back to the retina and harness light to the maximum.

Reflection of light due to the tapetum lucidum. Image taken from Exclusively cats

The tapetum lucidum is responsible for cat’s eyes appearing to glow in the dark and cat and dog’s pupils shine in blue/green when light falls upon the eye.

Tapetum lucidum shining on a dog. Photo Mireia Querol

WHY SOME ANIMALS HAVE THE EYES IN FRONT OF THE FACE WHILE OTHERS HAVE THEM ON THE SIDES ?

The position of the eye in mammals can be frontal, like a cat, or in the side, like a rabbit. This means distinct advantages:

  • Binocular vision (stereoscopic): allows a good estimation of distance, but the field of view is smaller. A 3D image is generated. It is typical of carnivores that should focus attention to their prey or primates that should calculate the distance between the branches.
  • Side vision (peripheral): allows each eye to send a different signals to the brain, so it is easier to notice their surroundings having a field of view of about 360 degrees. It is typical of herbivores, which must pay attention to the presence of potential predators .

    Visual field of a cat and a horse. The blind area is smaller in hervibores. Source: Sjaastad, Sand and O. Hove K. Photo taken from Eye Opener

WHY GOATS HAVE AN HORIZONTAL PUPIL?

In addition to the position of the eyes, the shape of the pupil is also related if you are a predator or a prey. Goats or horses have horizontal pupils, while cats like the margay have it vertical.

Pupil of a goat (horizontal) and a cat (vertical) Photo: Wikimedia Commons

Banks  says that “to calculate distances predators basis on stereoscopic vision (works better with a small pupil) and sharpness (works best with a larger one). Vertical pupils are small horizontally and large vertically”.

In the case of terrestrial prey attacked by predators, the tendency of the pupil is being horizontally because “can gather more light and and also reduces the sunlight, which could dazzle “. Exceptions such as rabbits or mice with a circular pupil, are because they have to pay attention also to the sky, from where a bird of prey can attack.

WHAT IS THE THIRD EYELID?

Some animals have the nictitating membrane (“third eyelid”), a transparent or translucent membrane that is used to protect and moisten the eye without losing visibility. Camels, seals and polar bears have it complete, whereas in other mammals, such as dogs or humans remains only reduced.

Nictitating membrane in a feline. Photo by Editor B

IS IT TRUE THAT DOGS AND BULLS SEE IN BLACK AND WHITE ?

Actually dogs and cats are able to detect colors, particularly gray, yellow and blue in softer tones. Cats may be able to perceive more colours.

Visible spectrum by a dog and a human. Source

In the case of bulls, it is also spread the myth that rage against the red colour or see in black and white. Actually bulls have dichromatic vision, like most diurnal mammals, since they only have blue and green cones. Therefore, they can’t see red, but it does not mean they see in black and white.

AND OTHER MAMMALS?

Horses see in blue and red tones. Most rodents see in black and white. Most species of the family of goats, sheeps and bulls see from green to violet. In addition, recent studies indicate that many mammals (especially nocturnal ones), contrary to what was believed, also can perceive ultraviolet radiation: rats and mice, reindeer, possibly cats and dogs, cows, pigs, ferrets, okapi…

We finish with a BuzzFeed video with the simulation of vision of some animals. If you have more questions about animal’s vision leave it in the comments!

REFERENCES

Evolution for beginners 2: coevolution

After the success of Evolution for beginners, today we’ll continue  knowing the basics of biological evolution. Why  exist insects that seem orchids and vice versa? Why gazelles and cheetahs are almost equally fast? Why your dog understands you? In other words, what is coevolution?

WHAT IS COEVOLUTION?

We know that it is inevitable that living beings establish symbiotic relationships between them. Some depend on others to survive, and at the same time, on elements of their environtment as water, light or air. These mutual pressures between species make that evolve together, and as one evolve as a species, in turn it forces the other to evolve. Let’s see some examples:

POLLINATION

The most known process of coevolution is pollination. It was actually the first co-evolutionary study (1859) by Darwin, although he didn’t use that term. The first to use the word coevolution were Ehrlich and Raven (1964).

Insects existed long before the appearance of flowering plants, but their success was due to the discovery that nectar is a good reserve of energy. In turn, the plants found in the insects another way more effectively to carry pollen to another flower. Pollination by the wind (anemophily) requires more production of pollen and a good dose of luck to at least fertilize some flowers of the same species. Many plants have developed flowers that trap insects until they are covered with pollen and then set them free. These insects have hairs in their body to enable this process. In turn some animals have developed long appendages (beaks of hummingbirds, butterflies’ proboscis…) to access the nectar.

Polilla de Darwin (Xantophan morganii praedicta). Foto de Minden Pictures/Superstock
Darwin’s moth (Xantophan morganii praedicta). Photo by Minden Pictures/Superstock

It is the famous case of the Darwin’s moth (Xanthopan morganii praedicta) of which we have already talked about. Charles Darwin, studying orchid Christmas (Angraecum sesquipedale) saw that the nectar was 29 cm inside the flower. He sensed that there should exist an animal with a proboscis of this size. Eleven years later, Alfred Russell Wallace reported him that the Morgan’s sphinxs had proboscis over 20 cm long, and a time later they were found in the same area where Darwin had studied that species of orchid (Madagascar). In honor of both it was added “praedicta” to the scientific name.

There are also bee orchids that mimic female insects to ensure their pollination. To learn more about these orchids and the Christmas one, do not miss this post by Adriel.

Anoura fistulata, murcielago, bat
The bat Anoura fistulata and its long tongue. Photo by Nathan Muchhala

But many plants not only depend on insects, also some birds (like humming birds) and mammals (such as bats) are essential to pollination. The record for the longest mammal tongue in the world is for a bat from Ecuador (Anoura fistulata); its tongue measures 8 cm (150% of the length of its body). It is the only who pollinates one plant called Centropogon nigricans, despite the existence of other species of bats in the same habitat of the plant. This raises the question of whether evolution is well defined, and occurs between pairs of species or it is diffuse due to the interaction of multiple species.

PREDATOR-PREY RELATIONSHIPS

The cheetah (Acinonyx jubatus) is the fastest vertebrate on land (up to 115 km/h). Thomson’s gazelle (Eudorcas thomsonii), the second (up to 80 km/h). Cheetahs have to be fast enough to catch a gazelle (but not all, at risk of disappearing themselves) and gazelles fast enough to escape almost once and reproduce. The fastest gaelles survive, so nature selects in turn faster cheetahs, which are who eat to survive. The pressure from predators is an important factor that determines the survival of a population and what strategies should follow the population to survive. Also, the predators will find solutions to possible new ways of life of their prey to succeed.

Guepardo persiguiendo una gacela. Foto de Federico Veronesi
Cheetah hunting a Thomson’s gazelle in Kenya. Photo by Federico Veronesi

The same applies to other predator-prey relationships, parasite-host relationships, plants-herbivores, improving their speed or other survival strategies like poison, spikes…

HUMAN AND DOGS … AND BACTERIA

Our relationship with dogs since prehistoric times, it is also a case of coevolution. This allows, for example, to create bonds with just looking at them. If you want more information, we invite you to read this post where we talk about the issue of the evolution of dogs and humans in depth.

Another example is the relationship we have established with the bacteria in our digestive system, essential for our survival. Or with pathogens: they have co-evolved with our antibiotics, so using them indiscriminately has favored these species of bacteria to develop resistance to antibiotics.

THE IMPORTANCE OF COEVOLUTION

Coevolution is one of the main processes responsible for the great biodiversity of the Earth. According to Thompson, is responsible for the millions of species that exist instead of thousands.

The interactions that have been developed with coevolution are important for the conservation of species. In cases where evolution has been very close between two species, if one become extint will lead to the extinction of the other almost certainly. Humans constantly alter ecosystems and therefore biodiversity and evolution of species. Just declining one species, we are affecting many more. This is the case of the sea otter (Enhydra lutris), which feeds on sea urchins.

Nutria marina (Enhydra lutris) comiendo erizos. Foto de Vancouver Aquarium
Sea otter (Enhydra lutris) eating sea urchins. Photo by Vancouver Aquarium

Being hunted for their fur, urchins increased number, devastated entire populations of algae (consumer of CO2, one of the responsible of global warming), seals who found refuge in the algae nonexistent now were more hunted by killer whales… the sea otter is therefore a key species for the balance of this ecosystem and the planet, as it has evolved along with urchins and algae.

Coevolutive relations between flowers and animals depend on the pollination of thousands of species, including many of agricultural interest, so we must not lose sight of the seriousness of the issue of the disappearance of a large number of bees and other insects in recent years. A complex case of coevolution that directly affects us is the reproduction of fig.

TO SUMMARIZE

As we have seen, coevolution is the evolutionary change through natural selection between two or more species that interact reciprocally.

It is needed:

  • Specificity: the evolution of each feature of a species is due  to selective pressures of the feature of the other species.
  • Reciprocity: features evolve together.
  • Simultaneity: features evolve simultaneously.

REFERENCES

MIREIA QUEROL ALL YOU NEED IS BIOLOGY

The thylacine: we extinguished it

Today marks 79 years of the death of the last known thylacine, Benjamin, at the zoo in Hobart (Tasmania). The thylacine, Tasmanian wolf or Tasmanian tiger is one of the classic examples of extinct animals by humans. Its fame is due to its relatively recent extinction, its strange anatomy and the existence of videos of the last thylacine, which transmits certain uneasiness to know that no longer exists. Do you want to know their characteristics, the causes of their disappearance and their cloning project?

THE THYLACINE, A MARSUPIAL

Despite its many names, the thylacine (Thylacinus cynocephalus*) was not related to wolves or tigers (placental mammals), as it was a marsupial animal. Marsupials are a mammals’ infraorder in which the young is born at a very early stage of development, almost in embryonic state. The best known representatives are kangaroos, koalas, wallabies, possums and bandicoots.

Un dels pocs llops marsupials que es conserven taxidermitzats en el món. Museo nacional de Ciencias Naturales, Madrid. Foto: Mireia Querol
One of the few preserved thylacine taxidermy in the world. Museo Nacional de Ciencias Naturales, Madrid. Photo: Mireia Querol

After a very short gestation, newborn moves to one of the mother‘s nipples where is seized several months. In most marsupials, nipples, -and therefore the newborn- are protected by a pouch. When the brood completes its development, it will release the nipple and leave the pouch to explore the outside. Look in the following video the birth and migration of the embryo of a red kangaroo:

DESCRIPTION

The thylacine was native of Australia and Papua New Guinea, but in the seventeenth century (arrival of European settlers Oceania) was found only in Tasmania.

mapa tilacino, thylacine distribution, tigre de tasmania, lobo de tasmania
Old thylacine distribution. Map by Discover Life

It was an animal with physical traits of wolf, tiger and kangaroo due to convergent evolution, which made him a unique case and an enigma to science before their taxonomy was known. Its closest relative is the Tasmanian devil (Sarcophilus harrisii).

He looked like a big dog with a thick, stiff tail. Its weight was about 30 kg on average. The fur was short, gray-brown with 13-20 vertical black stripes at the rear. It is estimated that lived between 5 and 7 years in the wild.

Instal·lació d'exemplars dissecats. Foto: South Australian Museum
Display of taxidermy thylacines. Photo: South Australian Museum

It was capable of bipedal jumps and upright posture for short periods of time. They were also good swimmers. The anatomy of the thylacine when stood up, with its tail resting on the ground, reminds the kangaroo as evidenced by the following filming of 1933:

FEEDING

The thylacine was exclusively carnivorous, feeding on kangaroos, emus, wallabies and wombats. It was a solitary and crepuscular hunter who caught their prey by ambushes, as it was not very fast. It could turn the palm of the leg up like cats do. This increased movement of the leg would have allowed them subdue prey more easily after a surprise attack. In contrast, animals with reduced mobility in the leg, as some canines, prefer the persecution of the ambush and often hunt in herds.

Benjamin abriendo la boca en una respuesta a una amenza similar a un bostezo. Zoo de Beaumaris, foto de David Fleay.
Benjamin gasping similarly to yawning in response to a threat. Hobart Zoo. Photo by David Fleay.

Another unique feature was the ability it had to open its mouth. Equipped with 46 teeth, its powerful jaws could be opened at an angle of 120 degrees, allowing him to swallow large chunks of meat.

La impresionante capacidad bucal del tilacino. Foto: desconocido
The thylacine’s impressive buccal capacity. Photo: video capture by David Fleay

Look in the following video the last moving record of Benjamin (1933), from which was obtained the above screenshot:

To view the 7 videos that remain from this fantastic animal, enter The Thylacine videos.

REPRODUCTION

Thylacines could reproduce from June to December. It were born 2-4 pups per litter, who spent three months in the pouch but were still dependent on its mother‘s milk more than nine months. Unlike many marsupials, in the thylacine pouch opened to the rear of the body.

tilacino embarazada, cria tilacino
Only existing photographs of females with brood in the pouch. Photo taken from The Thylacine Museum

EXTINCTION

Australian Aborigines already knew and hunted the thylacine, as seen in their 1000 b.C art. The first possible thylacine footprints discovered by Europeans are from 1642, although it was not until 1808 that a detailed description of the species was made.

tilacino cazado
Thylacine hunted in 1869. Photo of public domain

There are several hypotheses that point to the extinction of the Tasmanian tiger, in the majority, humans are the main blamable. Like it happens nowadays in Spain, the Tasmanian wolf was quickly accused of killing cattle and hen, so despondent rewards were offered for the animal and was the subject of an intensive hunt. Later research has concluded that its jaw was not strong enough to kill an adult sheep.

Única imatge existen d'un llop marsupial amb una presa. Investigacions recents suggereixen que es tracta d'un muntatge amb un especimen dissecat per donar-li mala fama. Foto de H. Burrell
Only existing picture of a thylacine with a prey. Later research suggest that is a farce with a taxidermy specimen to give them bad reputation. Photo by H. Burrell (1921)

With the colonization of Australia, the habitat and prey of the thylacine were diminished drastically. They were also victims of introduced species on the continent by humans, such as dogs, foxes and dingoes (wolf subspecies). It is also probably that suffered some diseases that lead them to death.

ültimo tilacino salvaje cazado por Wilfred Batty. Foto: desconocido (Wikimedia commons)
Last wild thylacine hunted by Wilfred Batty (1930). Photo: unknown (Wikimedia Commons)

In 1920 the thylacine was already on the verge of extinction. In 1930, it was hunted by a farmer the last known wild specimen and in 1933 arrived at Hobart Zoo the nicknamed Benjamin. In 1936, he was forgotten outside his cage and did not survive the freezing temperatures at night. 59 days before, it had been approved officially the protection of the species.

Only 128 years after his “discovery” the last thylacine died. Photo by David Fleay colored by Neitshade

After the 50 years required by the scientific community without any sightings or evidence of its existence, the thylacine was officially declared extinct by IUCN in 1986. Many claim to have seen the thylacine and even filmed one in the wild, but there are no no definitive evidence.

CURRENT RESEARCH

The International Thylacine Specimen Database is an international database that compiles all existing records of the Tasmanian wolf (museum specimens, bones, photos, videos…). Since 1999, there have been attempts to bring the thylacine back to life by cloning techniques, which have been unsuccessful. In 2008, Australian scientists were able to extract DNA from specimens preserved in alcohol and activate a gene implanting it in a mouse embryo and in 2009 the complete sequencing of mitochondrial DNA was published. The elusive goal is to activate the complete genome of thylacine, to have a real possibility of cloning. But if that happens, what are the ethical, economic and scientific implications of the reappearance of an extinct species? The debate is still open.

*Thylacinus cynocephalus from greek θύλακος (thylakos, “pouch”) and κυνοκἐφαλος (kinokefalos, “dog-headed”).

REFERENCES

MIREIA QUEROL ALL YOU NEED IS BIOLOGY

Meet present velociraptors

There are some stories about eagles who kidnap children, movies about murderer birds… But it really exist a bird which can kill a person? Are birds of prey the most dangerous birds? Keep reading to find out more.

THE CASSOWARY

According to the Guinness Book of Records, the most dangerous bird in the world is the cassowary. Cassowaries (family Casuariidae), like the emu (with whom it is related) and the ostrich, are flightless birds and good runners (up to 50 km/h). They are also good swimmers and can jump up to almost 2 meters. They live in New Guinea, north of Australia (Queensland) and neighboring islands (Ceram, Aru).

Casuario (casuarius unnapendiculatus). Foto de Quartl
Northern cassowary (Casuarius unnapendiculatus). Photo by Quartl

There are three species: the Southern cassowary (Casuarius casuarius), the Dwarf cassowary (Casuarius bennetti) and the Northern cassowary (Casuarius unappendiculatus). The largest of all is the Sourthern cassowary, in which we will focus in this article. Its name comes from Papua and means “horned head”.

Besides the size (1.80 m tall and weighing 70 kg, females are larger than males), highlighting the Southern cassowary is their blue and red neck, plucked, with two hanging pieces of skin (wattles), along with a casque that crowns the head, which is higher in the female. This casque is made up of trabecular bone (spongy bone) covered with hard skin (keratinized), which helps make their way through the dense vegetation of the rainforest where they live or for sexual attraction. It can also be a sign of the age, health and status of the animal respect their peers. It is estimated that they can live up to 12 to 19 years in the wild.

Primer plano de un casuario. Foto de Nick Hobgood.
Foreground of a Southern cassowary (Casuarius casuarius). Photo by Nick Hobgood.

The plumage is black, shiny and loose, giving it an aspect like hair. The tips are sharp and used as a defense. But the real danger of the cassowary falls upon its legs and feet, as one of its three fingers has a claw of about 10-12 cm long.

pies, peus, garra, uña, casuario, feet, foot, cassowary
Cassowary feet, in which can be seen its inner finger modified as a powerful claw. Photo by Christian Ziegler

DIET

The cassowary feeds mainly on fruits in the ground, which are swallowed whole. This makes them important seed dispersers, up to 70 different species. Their diet is completed with invertebrates such as insects, small vertebrates and fungi.

quandong, cassowary, eating, fruit
Cassowary eating quandongs, one of its favorite fruits. Photo by Christian Ziegler

REPRODUCTION

Cassowaries are birds of solitary habits, they meet only in breeding season (June to October). The female is dominant over the male and can mate with several males, putting different clutches on the floor.

cassowary, eggs, huevos, casuario, ous, casuari
Cassowary eggs are green coloured. Foto de Christian Ziegler

The males are responsible for incubating the eggs (4-8) for 50 days and take care of the chicks up to one year and four months. These have a plumage with brown, black and white stripes, they turn brown at 5 months of age. The final color and helmet appear when they are between 2 -4 years old.

casuario, pollitos, chicks, cassowary, casuari, pollets, iphone photo
Cassowary with its chicks. Photo by Kaisa Breeden

BEHAVIOUR

They are quiet and peaceful but highly territorial birds. When disturbed or threatened, they do not hesitate to violently attack with their powerful legs and beak. They attack like it is believed Velociraptors did: cassowaries make big jumps and kick their opponents eviscerating them with their powerful claw as if it were a dagger, and causing internal injuries because of blows. The cassowary has killed at least two people in Australia (2009 data) and probably some more that has not been documented in native populations. There have also been cases of bone fractures in people, such as ribs, legs …

In this video you can see how a cassowary attacks:

CONSERVATION AND THREATS

Although they are not dangerous to humans unless they are bothered, the main threat cassowaries suffer is the destruction of their habitat (replacement of the forest by cultivated fields) and forest fragmentation, which prevents access to food and other reproductive groups. There are also frequent car accidents in Australia and attacks of domestic dogs to cassowary chicks. Finally they are also victims of uncontrolled hunting in the area of New Guinea.

Australia, señal de tráfico, casuario, cape tribulation, cassowary, traffic signal
Traffic signal in Cape Tribulation, Australia, warning of the presence  of cassowaries. Photo by Mireia Querol

The Southern cassowary is classified as Vulnerable in the UICN Red List as well as the Northern cassowary. The dwarf cassowary is near threatened. Cassowaries in Australia live in protected areas, and there are also specific conservation plans by Queensland Parks and Wildlife Service. There are no reliable population data in New Guinea.

As we have seen, the cassowary is a spectacular bird that arouse great respect but is in danger. We encourage you to leave your comments and your experiences about it if you have traveled to their habitat and have been lucky enough to see one in the wild.

REFERENCES

 MIREIA QUEROL ALL YOU NEED IS BIOLOGY