Arxiu d'etiquetes: tardigrade

The Loch Ness Monster and Yeti: Do they exist?

The Loch Ness Monster, Yeti, Chupacabras, Bigfoot, Kraken… we’ve all heard about them once and we even doubted their (in)existence. What is the truth about these creatures? Are they real? If not, what answers gives science to refute it? Find out in this article.

CRYPTOZOOLOGY

Cryptozoology is a pseudoscience, uses scientific terms but is based on beliefs rather than evidence and does not use the scientific method. It tries to find animals that have not been confirmed by science, called cryptids. Usually are beings appeared in myths and legends, but also extinct species that it ensures they have been seen at present, as the thylacine or dinosaurs (non-avian ones). You just have to do a search in internet to find fake photos that won’t mislead the most gullible person, but when the stories are installed in the collective memory, supporters of cryptozoology increase.

sirena, juan cabana, sirena real, mermaid, real
The siren of Maracaibo, an internet viral cryptid. Despite being a sculpture of Juan Cabana, some people still believe in these fake beings. Photo: unknown

Cryptozoology usually tries to add features of real animals to cryptids to make them more credible, and even appropriates of the species discovered by biology (zoology), like when they say the Kraken is actually a giant squid.

THE LOCH NESS MONSTER

Nessie it is the most famous cryptid, a gigantic aquatic animal which is supposed to live in Loch Ness in Inverness, Scotland. As with all cryptozoological beings, evidence of their existence are fuzzy pictures and testimonies of sightings. Surely you’ve ever seen the most famous photo of the Monster:

 nessi, 1934, photo of the surgeon, the loch Ness monster, loch ness, monster
The first photo of Nessie, shot in 1934, was considered (and is considered) an evidence of their existence. 60 years after, Chris Spurling confessed that it was a fraud. Photo: Marmaduke Wheterell

This one, like all photos of the monster, have been proved to have been farces and frauds. However, they continue to fuel the myth: the annual profit in this part of Scotland are of several million euros. It is  not surprising that many lakes around the world have their own monster like Nahuelito, Caddy, Champ, Manipogo, Ponik …

WHY THE LOCH NESS MONSTER CAN’T EXIST ?

  • Its age: the first reference of a being in this lake dates back to 565. So today it would be… 1451 years old, much more than the oldest known animal: Ming the clam (507 years old). Or even more, as some cryptozoologists argue that it could be a plesiosaur or a similar animal (extinct over 65 million years ago) about 20 meters long and 10-20 tons.

     Loch Ness, otter, elephant
    Or maybe it was just an otter… Photo: Jonathan Wills
  • Origins: if it was an animal from the Age of Dinosaurs, or their descendants, it is impossible to have always lived in the lake, which was frozen since the last Ice Age until about 12,000 years ago. There are no ways of connection within the lake and the sea, there are no sightings of the montser outside the lake, so ti could never go out to the sea to feed, for example.  Assuming also Nessie was an aquatic reptile, his preference would be subtropical waters, not the cold waters of Inverness (6 ° C on average).
  • Family of Nessies: the only possible explanation for the continued existence for thousands or millions of years, is that there are no one, but at least 100 individuals like Nessie to keep a viable population, according to population ecology. The minimum viable population is the smallest isolated population having 99% chance to stay alive for 1000 years (Shaffer, 1981). In addition, the Loch Ness is 56.4 km long and 226 m deep, there is an obvious lack of space for all of them (in addition to that sightings would constant).
  • Lack of corpses: in the case that there was a group of plesiosaurs, sooner or later their bodies should appear in the bank and no one single corpse has been found.

    Elephant swimming. In 1933, the year with more sighntinghs, a circus toured the area. Its elephant apparently bathed in the lake several times. Photo: Jeremy Tucker
  • Insufficient food: the lake is deep, long and narrow (32 km x 1.6 km). As the base of the food chain on Earth are plants, in aquatic areas are phytoplankton, algae and plants that can sustain herbivores and carnivores. Loch Ness has a little surface area exposed to the sun, so do not get enough sunlight to do a massive photosynthesis. In addition, the water is dark because has turf in suspension, preventing the existence of light from a few meters depth. It is so unproductive that it could not survive a predator of more than 300 kilos. Obviously, there are few animals that are totally insufficient  for feeding one or more animals of 20 tonnes.

    cadena trofica, red alimenticia, xarxa tròfica,
    Food chain of a freshwater environment. The arrows indicate the direction of energy from one link to another. Picture: unknown
  • Lack of evidence with the latest technologies: BBC has tracked the lake several times with sonar and satellite navigation technology with negative results. Neither mini-submarines or 24 hours webcams have found no sign of the monster.

    THE YETI, THE ABOMINABLE SNOWMAN

    The second most famous cryptid is a giant bipedal ape living in the Himalayas. Or in North America (Bigfoot), Canada (Sasquatch) Almasty (Russia), Hibagon (Japan), Yowy (Australia)… Like Nessie, Bigfoot moves millions of euros/dollars and each country has its own. Also is suggested that could be some kind of extinct hominid, a Neanderthal, a  Homo erectus or a Gigantopithecus .

    yeti, huella, footprint, petjada
    Photograph which revived the legend of the Yeti (1951). Photo: Eric Shipton

    As with all cryptids, evidences are based on eyewitness sightings, blurry photos or with doubtful origin. But in this case there are hair samples ensuring that belong to the Yeti. What science says ?

    DNA ANALYSIS

    The current understanding of genetics has allowed us to establish a more precise family relationships and identify living beings through analysis of DNA. So Bryan Sykes (Oxford University) led a study that analyzed more than 30 hair samples preserved in Buddhist temples, museums and private collections. Result: horsehair, bison, human, raccoon, cow, wolf, coyote… but none of the Yeti .

    The good news for zoology is that two hair samples match the DNA of a polar bear fossil, which could belong to a bear species unknown until now or a variety of polar bear of another color (golden-brown).

    PAtterson-gimlin film, bigfoot
    The most famous photo of Bigfoot is a snapshot of a video taken by Patterson-Gimlin

    THE CHUPACABRAS

    The Chupacabras (“goat-sucker”) is supposed to be a creature that kills and sucks the blood of farm animals without spilling a drop. Definitions are multifarious, bright red eyes, scales, bipedal, spikes on the back… also alleged dead Chupacabras are reported:

    mexico chupacabras
    The alleged chupacabras carcasses are usually canines with scabies who have lost hair, raccoons, or in this case a flying fox. Photo: unknown

    The Chupacabras has the distinction of operating in latin countries: Venezuela, Puerto Rico, Mexico, Argentina, Spain, Chile… The alleged habitat of chupacabras clashes with biogeography: a branch of science that studies the distribution of living beings on our planet .

    Knowing a basics of biological evolution and climate we can think like biogeographers: species are distributed according to their habitat and have adapted to the different areas and climates. No one would think of a frog living in the Sahara desert, for example. But Chupacabras seems to not care: inhabits a huge variety of landscapes between two continents and several islands, but of course, has a predilection for Spanish-speaking places. Nothing to do with biology: it is the product of a legend of oral tradition.

    ZOOLOGY VS CRYPTOZOOLOGY

    In conclusion, zoology is the branch of biology that to certify that it has discovered a new species must:

Tardigrades: animals with superpowers

The smallest bears in the world have almost superhero abilities. Actually, they are not bears: water bears is the popular name of tardigrades. They are virtually indestructible invertebrates: they can survive decades without water or food, to extreme temperatures and they have even survived into outer space. Meet the animal that seems to come from another planet and learn to observe them in your home if you have a microscope.

WHAT IS A TARDIGRADE?

Oso de agua (Macrobiotus sapiens) en musgo. Foto coloreada tomada con microscopio electrónico de barrido (SEM): Foto de Nicole Ottawa & Oliver Meckes
Water bear (Macrobiotus sapiens) in moss. Colored photo taken with a scanning electron microscope (SEM). Photo by Nicole Ottawa & Oliver Meckes

Tardigrades or water bears, are a group of invertebrates 0.05-1.5 mm long that preferably live in damp places. They are especially abundant in the film of moisture covering mosses and ferns, although there are oceanic and freshwater species, so we can consider they live anywhere in the world. Even a few meters away from you, in the gap between tile and tile. In one gram of moss they have find up to 22,000 individuals. They are found in Antarctica under layers of 5 meters of ice, in warm deserts, hot springs, in mountains 6,000 meters high and abyssal ocean depths: they are  extremophiles. It is estimated that over 1,000 species exist.

MORPHOLOGY

Its popular name refers to their appearance, and the scientific name to their slow movements. Their bodies are divided into five segments: cephalic, with its tube-shaped mouth (proboscis) with two internal stilettos and sometimes simple eyes (ommatidia) and sensory hairs, and the remaining 4 segment with a pair of legs per segment. Each leg has claws for anchoring to the ground.

Vista ventral de un tardígrado donde seobservan los cinco segmentos del cuerpo. Foto de Eye Of Science/Photo LIbrary
Bottom view of a Tardigrade where the five segments of the body are observed. Colored photo taken with a scanning electron microscope (SEM). Photo by Eye Of Science/Science Photo Library
Tardigrade. Coloured scanning electron micrograph (SEM) of a freshwater tardigrade or water bear (Echiniscus sp.). Tardigrades, are tiny invertebrates that live in coastal waters and freshwater habitats, as well as semi-aquatic terrestrial habitats like damp moss. They require water to obtain oxygen by gas exchange. In dry conditions, they can enter a cryptobiotic tun (or barrel) state of dessication to survive. Tardigrades feed on plant and animal cells and are found throughout the world, from the tropics to the cold polar waters.
Tardigrade (Echiniscus sp.) In which you can see the claws. Colored photo taken with a scanning electron microscope (SEM). Photo de Eye Of Science/Science Photo Library

Look at this video of Craig Smith to see tardigrade’s movements in more detail:

FEEDING

With its mouth stilettos, tardigrades perforate plants and absorbe the products of photosynthesis, but they can also feed absorbing the cellular content of other microscopic organisms such as bacteria, algae, rotifers, nematodes… Some are predators too and can eat whole microorganisms.

Their digestive system is basically the mouth and a pharynx with powerful muscles to make sucking motions that opens directly into the intestine and anus. Some species defecate only when they shed.

Detalle de la boca de un tardígrado. Foto de
Detail of the mouth of a tardigrade. Colored image of scanning electron microscope (SEM). Photo by Eye Of Science/Science Photo Library

INTERNAL ANATOMY

They have no circulatory or respiratory system: gas exchange is made directly by the body surface. They are covered by a rigid cuticle which can be of different colors and is shed as they grow. With each moult, they lose oral stilettos, to be segregated again. They are eutelic animals: to grow they only increase the size of their cells, not their number, that remains constant throughout life

REPRODUCTION

Tardigrades generally have separate sexes (are dioecious) and reproduce by eggs (are oviparous), but there are also hermaphrodites and parthenogenetic species (females reproduce without being fertilized by any male). Fertilization is external and development is direct: they don’t have larval stages.

tardigrade egg, ou tardigrad
Tardigrade egg. Colored image of scanning electron microscope (SEM). Photo by Eye of Science/Science Photo Library

TARDIGRADE’S RECORDS

The tardigrades are incredibly resilient animals that have survived the following conditions:

  • Dehydration: they can survive for 30 years under laboratory conditions without a single drop of water. Some sources claim that resist up to 120 years or have been found in ice 2000 years old and have been able to revive, although it is likely to be an exaggeration.
  • Extreme temperature: if you boil one tardigrade survives. If you put it to temperatures near the absolute zero (-273ºC), survives. Their survival rate ranges from -270ºC to 150ºC.
  • Extreme pressure: they are capable of supporting from vacuum to 6,000 atmospheres, ie 6 times the pressure in the deepest point on Earth, the Mariana Trench (11,000 meters deep).
  • Extreme radiation: tardigrades can withstand bombardment of radiation at a dose 1000 times the lethal to a human.
  • Toxic substances: if they are immersed in ether or pure alcohol, survive.
  • Outer space: tardigrades are the only animals that have survived into space without any protection. In 2007 the ESA (European Space Agency) within the TARDIS project (Tardigrades In Space) left tardigrades (Richtersius coronifer and Milnesium tardigradum) for 12 days on the surface of the Foton-M3 spacecraft and they survived the space travel. In 2011 NASA did the same placing them in the outside of the space shuttle Endeavour and the results were corroborated. They survived vacuum, cosmic rays and ultraviolet radiation 1,000 times higher than that of the Earth’s surface. The project Biokis (2011) of the Italian Space Agency (ASI) studied the impact of these trips at the molecular level.

HOW DO THEY DO THAT?

The tardigrades are able to withstand such extreme conditions because they enter cryptobiosis status when conditions are unfavorable. It is an extreme state of anabiosis (decreased metabolism). According to the conditions they endure, the cryptobiosis is classified as:

  • Anhydrobiosis: in case of environmental dehydration, they enter a “barrel status” because adopt barrel shaping to reduce its surface and wrap in a layer of wax to prevent water loss through transpiration. To prevent cell death they synthesize trehalose, a sugar substitute for water, so body structure and cell membranes remain intact. They reduce the water content of their body to just 1% and then stop their metabolism almost completely (0.01% below normal).

    Tardígrado deshidratado. Foto de Photo Science Library
    Tardigrade dehydrated. Photo by Photo Science Library
  • Cryobiosis: in low temperatures, the water of living beings crystallizes, it breaks the structure of cells and the living being die. Tardigrades use proteins to suddenly freeze water cells as small crystals, so they can avoid breakage.
  • Osmobiosis: it occurs in case of increase of the salt concentration of the environment.
  • Anoxybiosis: in the absence of oxygen, they enter a state of inactivity in which leave their body fully stretched, so they need water to stay perky.

Referring to exposures to radiation, which would destroy the DNA, it has been observed that tardigrades are able to repair the damaged genetic material.

These techniques have already been imitated in fields such as medicine, preserving rat hearts to “revive” them later, and open other fields of living tissue preservation and transplantation. They also open new fields in space exploration for extraterrestrial life (Astrobiology) and even in the human exploration of space to withstand long interplanetary travel, ideas for now, closer to science fiction than reality.

ARE THEY ALIENS?

The sparse fossil record, the unclear evolutionary relatedness and great resistance, led to hypothesis speculating with the possibility that tardigrades have come from outer space. It is not a crazy idea, but highly unlikely. Panspermia is the hypothesis that life, or rather, complex organic molecules, did not originate on Earth, but travelled within meteorites in the early Solar System. Indeed, amino acids (essential molecules for life) have been found in meteorites composition, so panspermia is a hypothesis that can not be ruled out yet.

Foto de Eye Of Science/Photolife Library
Photo by Eye Of Science/Photolife Library

But it is not the case of tardigrades: their DNA is the same as the rest of terrestrial life forms and recent phylogenetic studies relate them to onychophorans (worm-like animals), aschelminthes and arthropods. What is fascinating is that is the animal with more foreign DNA: up to 16% of its genome belongs to fungi, bacteria or archaea, obtained by a process called horizontal gene transfer. The presence of foreign genes in other animal species is usually not more than 1%. Could be this fact what has enabled them to develop this great resistance?

DO YOU WANT TO SEARCH TARDIGRADES BY YOURSELF AND OBSERVE THEM IN ACTION?

Being so common and potentially livIng almost anywhere, if you have a simple microscope,  you can search and view living tardigrades by yourself:

    • Grab a piece of moss of a rock or wall, it is better if it is a little dry.
    • Let it dry in the sun and clean it of dirt and other large debris.
    • Put it upside down in a transparent container (such as a petri dish),  soak it with water and wait a few hours.
    • Remove moss and look for tardigrades in the water container (put it on a black background for easier viewing). If lucky, with a magnifying glass you’ll see them moving.
    • Take them with a pipette or dropper, place them on the slide and enjoy! You could see things like this:

REFERENCES

MIREIA QUEROL ALL YOU NEED IS BIOLOGY