Arxiu d'etiquetes: nymphs

Sleep tight, don’t let the bed bugs bite!

Have you ever felt uncomfortable when hearing this expression or feared to find your bed infested with bed bugs? Yes, bed bugs exist. However, good news is that not all insects known as ‘bugs’ sting nor live inside our bed sheets.

What bugs really are? Are all of them harmful? Where can we find them? Find out their diversity through this post, and give up thinking that bugs are dangerous!

Which insects are called ‘bugs’?

When talking about ‘bugs’, people are unconscious about the true diversity of these organisms. Bugs, and more exactly true bugs, belong to the Heteroptera suborder, which includes more than 40,000 species worldwide; in fact, they are the largest group of insects with simple metamorphosis. Their most ancient fossil, Paraknightia magnífica, which was found in Australia, has been dated from the late Permian (260-251 MA).

The Heteroptera belong to the Hemiptera order, inside which we can find other suborders which were formerly classified as a single suborder (‘Homoptera’). Some of the suborders once classified as ‘Homoptera’ include some well-known organisms, such as cicadas (Cicadidae) and aphids (Aphididae).

How can we recognize them?

Heteropterans appear in different forms and sizes. The tiniest specimens belong to the Anthocoridae, Microphysidae, Ceratocombidae, Dipsocoridae, Aepophilidae and Leptopodidae families, which are barely visible to the naked eye. Among the largest members there are some species of the Belostomatidae family, such as Lethocerus indicus (6.5-8 cm length). Despite this, they appear as a monophyletic group according to molecular data.

They show at least three synapomorphies:

  1. Piercing-sucking mouthparts, long, forming a stylet.

    Mouthparts of the predator Arilus cristatus (Reduviidae). Picture property of John Flannery on Flicker (CC 2.0).
  2. Paired odoriferous glands.
  3. Four-segmented antennae.

Furthermore, they have forewings (formally known as hemelytra) with both membranous and hardened portions, which gives its name to the group (Heteroptera, from the Ancient Greek ‘hetero’, different; ‘-pteron’, wings).

Pentatomidae. The proximal part of forewings is hardened, while the distal one is membranous. Picture property of Mick Talbot on Flickr (CC 2.0).

Ecology

Life cycle

Heteropterans undergo a simple metamorphosis, so youths or nymphs and adults almost show no differences and cohabit in the same habitat. After hatching, nymphs molt several times until reaching the last nymphal molt, known as imaginal molt, through which they reach adulthood.

Life cycle of heteropterans. Picture property of Encyclopedia Britannica, Inc. (link).

Adults differ from nymphs on having wings, a new disposition of odoriferous glands openings, a different number of tarsal (legs) and antennal segments, ocelli, ornaments (spines and glandular hairs), sexual traits on the terminal abdominal segments and sometimes a different coloration, besides a bigger size and a way harder tegument.

Nezara viridula nymph (Pentatomidae), still wingless. Picture property of S. Rae on Flickr (CC 2.0)

Communication and defense

Specimens of the same species emit volatile pheromones produced by their odoriferous glands as a way of communication. So, they can expel aggregation pheromones and sexual pheromones to gather in a point or to find a mate, respectively. In some species, it has also been documented the emission of sounds produced by stridulation, that is, producing sounds by rubbing together certain body parts.

Heteropterans develop passive and active defense mechanisms:

  • Among passive mechanisms, we can highlight the own body shapes (e. g., smooth and rounded structures which difficult their capture by predators), the inactivity as a way to go unnoticed by other organisms, and the crypsis or mimicry. Some examples of crypsis or mimicry are 1) color mimesis (homocromy) 2) shape mimesis (homotopy), through which they imitate structures of their environment, either plants or animals (e. g. ant-mimicry or myrmecomorphy) and 3) disruptive mimesis, that is, their outlines get blurred with the environment, so it gets difficult for predators to find them.

Leptoglossus occidentalis (Coreidae), with their wide tibiae that look like leaves. Picture property of Giancarlodessi (CC 3.0).

Myrmecoris gracilis (Miridae), a clear example of ant-mimicry or myrmecomorphy. Picture property of Michael F. Schönitzer (CC 4.0).

  • Some active mechanisms are 1) escaping, 2) biting, 3) the detachment of some appendices to confuse predators and 4) the emission of stink or irritating substances by their odoriferous glands, which in most of cases they acquire from plants they feed on. Others emit stridulating sounds.

Life forms and diversity

Even though most people know something about heteropterans due to the famous bed bugs, feeding on blood is far from being the only life form among true bugs.

  • Terrestrial

Most heteropterans inhabit terrestrial environments, either on plants or on the ground as phytophagous (they feed on vegetal fluids) or predators of other insects. There are also some terrestrial heteropterans that feed on roots or on fungi that develop under tree bark. Some examples of terrestrial phytophagous families are Pentatomidae and Coreidae. Among predators, which use their stylet to inoculate proteolytic agents inside their preys to dissolve their content and then suck it, there are a lot of members from Reduviidae family.

  • Aquatic and semiaquatic

Aquatic and semiaquatic forms have special adaptations to live in water, like hydrofuge hairpiles which repel the water. Most of them live in lakes and rivers, either on their surface (semiaquatic) or submerged.

Semiaquatic species usually have long legs and long antennae, which together with the hydrofuge hairpiles let them to stand on water. Water striders (Gerridae), which are very abundant in Europe, are a clear example of this life form.

Water striders (Gerris sp.). Picture property of Webrunner (CC 3.0)

Aquatic species usually have a pair of legs adapted to swim. A good example of this are the members of the family Notonectidae or backswimmers, which have the hind legs fringed for swimming.

Notonecta sp. (Notonectidae). Picture property of Jane Burton/Bruce Coleman Ltd. (link).

Despite living in water, aquatic heteropterans need surface air to breath, so they go out of water periodically. They present different strategies to absorb oxygen, such as swallowing air that goes directly to the respiratory or tracheal system through a siphon (Nepidae) or capturing air bubbles with their hydrofuge hairpiles (Nepidae). Other simply get covered of a tiny air layer using their hydrofuge hairpiles.

  • Hematophagous

Finally, there are heteropterans that feed on blood and live as bird and mammal parasites. This is the case of the Cimicidae family (e. g. Cimex lectularius, the bed bug) and some groups of Reduviidae, such as the members of the subfamily Triatominae, which are also known for being vectors of the Chagas disease in the center and south of America (being Triatoma infestans its main vector).

Cimex lectularius or bed bug nymph. Public domain.

Triatoma sp. (Triatominae). Picture property of Bramadi Arya (CC 4.0).

Scientific interest

  • They help to regulate some wood and crop pests, having an important role in integratative pest management. This is the case of some predator heteropterans from the Reduviidae, Anthocoridae, Miridae, Nabidae and Geocoridae families. However, some phytophagous heteropterans can act as pests too.
  • They have been an interesting scientific model for the study of insect physiology.
  • They are an important element on human diet in some countries, being Pentatomidae one of the most consumed families. Some aquatic heteropterans, such as Lethocerus sp. (Belostomatidae) are very appreciated as food in some Asiatic countries, like Vietnam and Thailand.

Lethocerus sp. Picture property of Judy Gallagher on Flickr (CC 2.0).

  • Some of them are disease vectors or a cause of discomfort. The most classic example is the bed bug (Cimex lectularius), which has become a frequent pest in temperate regions; some Cimidae are also a threat for free range chickens and other farm birds. In America, Triatominae are vectors of different diseases, being the most famous the Chagas disease (transmitted by a protozoan, Trypanosoma cruzi).

.                .                 .

All organisms on Earth are necessary for some reason: you only need to investigate about them. Even the true bugs!

References

Main picture property of Pavel Kirillov on Flickr, with license  Creative Commons 2.0. (link).

Why do insects metamorphose?

Most of insects undergo some kind of transformation process during their life cycle in order to reach adulthood -also known as imago phase- (e.g. butterflies). This process is named metamorphosis, although its essence is far from that of metamorphosis performed by amphibians. But, have you not ever wondered why they do this transformation? Which are the sense and the origin of the metamorphosis of insects?

Learn more about the different types of metamorphosis, the origin and sense of these transformations through this article.

Metamorphosis: what is that?

Metamorphosis of the Old World swallowtail (Papilio machaon) (Picture by Jens Stolt).

Metamorphosis is a biological process by which animals develop after birth involving huge transformations and/or anatomical restructurations (both physiological and anatomical) until reaching adulthood.

There are different groups of animals that develop by this process, however most of them don’t share the origin nor the nature of these transformations. Thus, while amphibian metamorphosis takes place by reorganization of youth preexistent organs, in insects it takes place a breaking of tissues and also the appearance of totally new cell clusters.

Ecdysis or molting

First of all, we must talk about molt in order to comprehend the metamorphosis of insects. What means molting? And why is it an essential process for insects and arthropods as a whole?

Every single animal regenerates its external tissues in some way, i.e., those tissues that are in contact with the environment and that protect the organism from external pressures. E.g. mammals regenerate their epidermal tissues periodically; a lot of reptiles shed off their skin frequently; but, what’s about arthropods?

Arthropods, which include the hexapods (group in which we can find all insects), are externally covered by a more or less hard exoskeleton. In contrast with other external animal tissues, the exoskeleton doesn’t detach progressively, and its lack of elasticity restricts the organism growth. So, this element becomes a barrier that limits their size while growing, and is for this that they have to break it and leave it away in order to keep on growing. This kind of molting is known as ecdysis, which is typical of ecdysozoa (arthropods and nematoda).

Take a look at this video of a cicada molting!:

Do all hexapods metamorphose?

The answer is NO. However, it’s necessary to go deeper into the explanation.

All hexapods molt in order to grow, but not all them undergo radical changes to reach adulthood (when they become able to breed). Thus, we can split hexapods into two main groups:

AMETABOLOUS HEXAPODS (No metamorphosis)

This group includes those hexapods traditionally known as Apterygota or wingless hexapods (Non insect hexapods –proturans, diplurans and colembolas- and wingless insects as Zygentoma or also known as Thysanura –e.g. silverfishes or Lepisma-) and Pterygota or winged insects that have suffered a secondary loss of their wings.

Specimen of Ctenolepisma lineata (Zygentoma) (Wikimedia Commons).

Since they have no wings at any moment of their life cycle, the youth phases of this kind of hexapods almost have no differences from the adult ones. Thus, the youth development is simple and they don’t undergo huge changes to acquire the adult physique; that is, there is no metamorphosis at any point of their life cycle. This kind of development is also known as direct development.

metamorfosis3
Direct development or ametabolous development (Picture from asturnatura.com).

Ametabolous hexapods can molt tens of times throughout their development (e.g. 50 times in silverfishes, more or less), even when they become sexually mature.

INSECTS THAT METAMORPHOSE

This group includes Pterygota insects or winged insects (except for the ones that have secondarily lost their wings).

Specimen of Sympetrum flaveolum (Picture by André Karwath)

In contrast of the ones which have been explained above, the youth phases of metamorphic insects are very different from the adult ones; so, after several successive molts they undergo their last change, through which it emerges a winged adult able to breed. After reaching this phase, these insects become unable to molt again.

Types of metamorphosis in insects

So, only Pterygota insects undergo a truly metamorphosis, thanks to which they become winged insects and also reach sexual maturity. But not all these insects perform the same kind of change.

There exist two main types of metamorphosis: the hemimetabolous one (simple or incomplete) and the holometabolous one (complex or complete). Which are their differences?

Hemimetabolous metamorphosis

In the simple, incomplete or hemimetabolous metamorphosis, young insects go through several successive molts until reaching adulthood (or imaginal) stage without going through a stage of inactivity (pupa) and/or stop feeding.

Just after hatching, we referred the newborn as a nymph, which resembles a little to the adult ones (but still not having wings nor sexual organs). Usually, nymphal phases and the adult ones don’t share feed sources nor habitat, so they occupy different ecological niches; in fact, most nymphs have aquatic habits and they go to live on land after reaching maturity (e.g. mayflies).

Haft
Adult specimen of the species of mayfly Ephemera danica (Imagen de Marcel Karssies).

In this kind of metamorphosis, nymphs go through some successive molts thanks to which wings are gradually formed and their organism becomes bigger. Finally, nymphs perform their last molt, after which the adult emerges: a winged organism that is able to breed.

Take a look to this scheme that sums up this process:

heterometabolo
______Hemimetabolous development of a _______grasshopper (imagen extraída de ________________asturnatura.com)

These insects are also called Exopterygota (from Latin exo- = “outside” + pteron = “wings”), because in these organisms the wings are progressively and visibly formed at the outside part of their body.

Holometabolous metamorphosis

In general terms, it’s considered the most radical metamorphosis in insects and also probably the most well known transformation by all of us. The most famous example is the one performed by lepidopterans (butterflies and moths); but there are also more insects that are holometabolous, such as coleopterans (beetles), hymenopterans (bees, wasps and ants) and dipterans (flies and mosquitoes).

In the complex, complete or holometabolous metamorphosis, insects are born as larvae, that is, a premature stage that doesn’t resemble anatomically nor physiologically to the adult. In addition, they don’t share feed sources nor habitat, as it is the case of hemimetabolous organisms. As in hemimetabolous insects, these larvae go through successive molts until reaching the size enough to undergo the metamorphosis, when they perform their last molt.

Beetle larva (“Curl grub” by Toby Hudson – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons).

After their last larval stage, larvae enter in a stage of inactivity, moment they stop feeding and remain motionless. This stage is known as pupal stage (when they become a pupa or a chrysalis in butterflies). Usually, larvae begin to resemble to the adults at the end of this stage due to the anatomical modifications that take place and also to the appearance of new organs and tissues.

Cetoine_global
Pupal stage of Cetonia aurata (Coleoptera) (“Cetoine global” by Didier Descouens – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons)

Once the transformation process ends, the organisms leave that motionless state and acquire their adult form that has wings and is totally mature.

In summary, the scheme of this process could be:

metamorfosis
Holometabolous development of a lepidopteran (Picture from _________________________astrunatura.com)

In contrast with hemimetabolous insects, the appearance of wings in holometabolous organisms takes place inside their body and become visible only at the end of the pupal stage. For this reason, they are also known as Endopterygota (from Latin endo-= “inside” + pteron=”wings”).

Origin and function of insect metamorphosis

Origin: the fossil record

Insects are, as we discussed in previous articles, one of the animals with greater evolutionary success. Between 40%-60% of all insect species are holometabolous (complete metamorphosis), because of what we deduce that holometabolous metamorphosis was positively selected during the evolution of this group. In fact, fossil records suggest that this kind of metamorphosis appeared only once, so all holometabolous insects derive from the same ancestor.

According to these data, wingless insects or ancient Apterygota and early winged insects were ametabolous. Then, all winged insects started to develop some kind of hemimetabolous metamorphosis during the Carboniferous and the Permian (300 Ma). Finally, the first insects considered as holometabolous appeared during the Permian period (280 Ma).

What could be the reason of this positively selection?

In the latest paragraphs, we talked about the different feeding sources and habitats of both youth and adult. The fact that different life stages of the same animal exploit different resources could prevent the intraespecífic competition (i.e. competition for resources between organisms of the same species). This fact would mean a great advantage for these organisms, so that holometabolous development, which is characterized for being divided in very different stages, could have been more successful than the hemimetabolous or the ametabolous.

Thus, we can say the main functional sense of metamorphosis could be to minimize the intraespecífic competition for resources. But there is still more: the more specialized are the different stages of an insect, the greater would be the chance to exploit more and better the resources. E.g. in parasitic forms, the differences between different stages tend to be huge, because the difficult situations they have to face require a specific specialization in each moment of the life cycle.

Sin título
Larva and adult of Danaus plexippus (monarch butterfly) (sources: larva picture by Victor Korniyenko, Creative Commons; adult picture of public domain).

.        .         .

So, likewise the appearance of wings promoted the expansion and diversification of insects worldwide, the metamorphosis could have acted as a diversifying engine by increasing the capacity to exploit more and better resources.

REFERENCES

Main picture by Steve Greer Photography.

Difusió-anglès

If the nymphs were plants, they would be water lilies

This week, I’m going to introduce water lilies, some flowers very nice and known for being important in the ornamentation.

INTRODUCTION

The Nymphaeaceae family has few species and most of them are freshwater aquatic plants in quiet places and commonly are known as water lilies. Because they are aquatic plants, the family’s name is derived from the Latin word nympha, as they have some similarity with nymphs, mythological beings with a predilection for the waters.

1024px-Rae_-_Water_Nymphs_(color)Water nymphs, water lilies can be seen around (Painting by Henrietta Rae, 1909).

The water lilies were originated in warm regions, but they are now subcosmopolitan and can be found in several parts of the world, living in ponds, lakes and freshwater streams.

MORPHOLOGICAL CHARACTERS

The water lilies are perennial aquatic plants, they live several years, and are rhizomatous, that is, they have a thickened stem below the soil at the bottom of the water. In some species, we see that some leaves are immersed and others are floating on the water surface, being sometimes even membranous (they have raised edges perpendicularly upward to avoid the ingress of too much water). When this morphological difference happens, we talk about heteromorphous leaves.

Flowering_victoriaWater lily's membranous leaves (Victoria amazonica) (Photo taken by Dirk van der Made).

Their flowers grown out of water and are constituted by a variable number of sepals, petals and stamens, which are helically born. Therefore, flowers are acyclic, that is, are asymmetrical or irregular because they have no symmetric plane. These flowers are solitary, not born grouped, and hermaphrodites, that is, both male (stamens) and female (ovary) sex organs occur in the same flower.

Nenufar-rosa Nymphaea tetragonaPygmy waterlily (Nymphaea tetragona)(Photo taken by Miguel303xm).

These perianth parts (petals and sepals) and stamens are free among them, therefore, they are not united or fused among them, and normally appear in large numbers. The stamens are different to several of other flowers, because they are laminar stamens, similar to the petals. Therefore, they are not filamentous, are thicker and wider.

DIVERSITY

Currently, the genera of water lilies which have more relevance are Nuphar, Nymphaea and Victoria, but there are also some others. Below I present some cases of very interesting species.

The tiger lotus or Egyptian white water-lily (Nymphaea lotus) is native of the Nile Valley and eastern Africa. It is prized as an ornamental and ancient Egyptians believed that the flower could give strength and power.

800px-Nymphaea_lotus4Egyptian white water-lily (Nymphaea lotus) (Photo taken by Meneerke bloem).

The yellow water-lily (Nuphar lutea) is typical of Europe, North Africa and the Middle East and, as the previous one, is also very ornamental. Furthermore, it has been long used in traditional medicine. Its roots were applied on the skin and seeds and roots were eaten to treat different diseases.

Nuphar_lutea_W160Yellow water-lily (Nuphar lutea) (Photo taken by Oksana Golovko).

Finally, I’d want to introduce the genus of Victoria, whose pollinitation is very curious. It has two American species: V. cruziana in Argentina and V. amazonica in the Amazon and Brazil. Plants of this genus are very big, with floating leaves reaching to 2 meters in diameter and with showy flowers which can reach up to 30 centimeters and are opened at evening.When these flowers are opened, strong scents and a little heat are released and with the whitish and beige colours of the petals, they result very attractive to the beetles (Coleoptera) that are feed of starch extensions on the flowers (starch bodies). The next morning, flowers are closed and the beetles are captured within, causing them to be permeated of pollen. At afternoon, flowers are reopened and allow beetles to escape. Then, as the flowers have been pollinated, their colour varies to pink and they also lose scent. Therefore, the beetles feel more attracted to white flowers that have not been pollinated yet. Finally, the pink flowers are dipped.

V. cruziana & V. amazonicaOn the left, V. cruziana (Photo taken by Greenlamplady); On the right, V. amazonica (Photo taken by frank wouters).

IMPORTANCE

Currently, several species are used as ornamentals, decorative. Furthermore, the water lilies can also be used to get food; the seeds and rhizomes of the genera Nymphaea and Victoria are edible. On the other hand, a very curious thing is that the nerves of the leaves of some species have been used to extract a liquid, which has been applied to treat snake bites.

I hope you liked the way the water lilies behave and all their tales and uses that are associated to them, although only for its beauty are charming. If you enjoyed, do not forget to share in different social networks. Thanks for your interest.

REFERENCES

Licencia Creative CommonsLicencia Creative Commons Atribución-NoComercial-CompartirIgual 4.0 Internacional.

Si les nimfes fossin plantes serien nenúfars

Aquesta setmana us vull presentar els nenúfars, unes flors ben maques i molt conegudes degut a la seva importància en ornamentació.

INTRODUCCIÓ

La família de les nimfeàcies (Nymphaeaceae) és una família amb poques espècies i la majoria d’elles són plantes aquàtiques d’aigua dolça en llocs calmats i vulgarment es coneixen com a nenúfars. Degut a que són plantes aquàtiques, el nom d’aquesta família prové de la paraula nympha del llatí, ja que tenen certa similitud a les nimfes, éssers mitològics amb predilecció per les aigües.

1024px-Rae_-_Water_Nymphs_(color)Nimfes aquàtiques, es poden apreciar nenúfars al seu voltant (Pintat per Henrietta Rae, 1909).

Les nimfeàcies són originaries de regions càlides, però actualment són subcosmopolites i és troben en moltes zones del món, habitant estancs, llacs i cursos d’aigua dolça.

CARACTERÍSTIQUES MORFOLÒGIQUES

Els nenúfars són plantes aquàtiques perennes, viuen varis anys, i rizomatoses, és a dir, tenen una tija engruixida sota el terra del fons aquàtic. En moltes espècies algunes fulles són submergides i les altres són flotants a la superfície de l’aigua, essent a vegades membranoses (tenen les vores aixecades perpendicularment cap amunt per evitar que entri massa aigua). Quan presenten aquesta diferència en el tipus de fulles parlem de fulles heteromorfes, de diferent forma.

Flowering_victoriaFulles membranoses de nenúfar (Victoria amazonica) (Foto de Dirk van der Made).

Les flors són emergides, creixen fora del aigua, i estan constituïdes per un nombre variat de sèpals, pètals i estams que neixen de manera helicoïdal. Per tant, són flors acícliques, són asimètriques o irregulars perquè no tenen cap pla de simetria. Aquestes flors són solitàries, no surten agrupades, i a més són hermafrodites, és a dir, presenten òrgans sexuals tant masculins (els estams) com femení (ovari) en la mateixa flor.

Nenufar-rosa Nymphaea tetragona"Ninfa venus" (Nymphaea tetragona)(Foto de Miguel303xm).

Aquestes peces del periant (pètals i sèpals) i els estams són lliures entre ells, és a dir que no estan soldats o fusionats entre ells, i normalment són nombrosos. Els estams, a diferència amb molts d’altres flors, són laminars, semblants als pètals. Per tant, no són filamentosos, sinó que tenen més gruix i són amples.

DIVERSITAT

Actualment els gèneres de nenúfars que tenen més rellevància són Nuphar, Nymphaea i Victoria, però també hi ha d’altres. A continuació presentaré algunes espècies i casos ben interessants.

El lotus egipci o lotus tigre (Nymphaea lotus) és originari de la vall del Nil i l’Àfrica oriental. És molt apreciat com a ornamental i antigament els egipcis crien que la flor donava força i poder.

800px-Nymphaea_lotus4Lotus egipci (Nymphaea lotus) (Foto de Meneerke bloem).

El nenúfar groc (Nuphar lutea)  és tipics d’Europa, el nord d’Àfrica i Mitjà Orient i, com l’anterior, també és molt ornamental. A més, ha estat utilitzat durant molt temps en la medicina tradicional. La seva arrel s’aplicava a la pell i es menjaven les seves rels i llavors per tractar diferents malalties.

Nuphar_lutea_W160Nenúfar groc (Nuphar lutea) (Foto de Oksana Golovko).

Finalment presentar al gènere Victoria, que és molt curiós pel seu tipus de pol·linització. Aquest te dues espècies americanes, V. cruziana a Argentina i V. amazonica en l’Amazones i Brasil.  Les plantes d’aquest gènere són molt grans, les fulles flotants arriben als 2 metres de diàmetre i fan flors vistoses de fins a 30 centímetres que s’obren durant la tarda-nit. Quan aquestes flors s’obren desprenen fortes olors i una petita escalfor, que juntament amb els clors blancs i groguencs que té, resulten molt atraients per als escarabats o coleòpters (Coleoptera) que s’alimenten de les extensions de midó que tenen les flors (cossos de midó). A la matinada següent les flors es tanquen i capturen als escarabats, fent que s’impregnin de pol·len. A la tarda següent les flors es tornen a obrir i deixen escapar als coleòpters. Llavors, com les flors ja han estat pol·linitzades es tornen d’un color rosat  i perden l’olor, deixant així que els escarabats es sentint atrets per les flors blanques que encara han de ser pol·linitzades. Finalment la flor rosada pol·linitzada es submergeix.

V. cruziana & V. amazonicaA l'esquerra, V. cruziana (Foto de Greenlamplady); A la dreta, V. amazonica (Foto de frank wouters).

IMPORTÀNCIA

Actualment moltes espècies són utilitzades com a ornamentals, decoratives. A més, les nimfeàcies també poden ser utilitzades per extreure aliments; les llavors i rizomes dels gèneres Nymphaea i Victòria es poden menjar. D’altra banda, una cosa ben curiosa és que dels nervis de les fulles d’algunes espècies s’han utilitzat per extreure un líquid que serveix per curar mossegades d’escurçons.

Espero que us hagi captivat la manera en que es comporten els nenúfars i totes les històries i usos que tenen associats, tot i que simplement per lo macos que són ja ens captiven. Si t’ha agradat no oblidis de compartir-lo a les diferents xarxes. Gràcies pel teu interès.

REFERÈNCIES

Licencia Creative CommonsLicencia Creative Commons Atribución-NoComercial-CompartirIgual 4.0 Internacional.

Si las ninfas fueran plantas serían nenúfares

Esta semana os voy a presentar a los nenúfares, unas flores muy bonitas y conocidas por su importancia en la ornamentación.

INTRODUCCIÓN

La familia de las ninfeáceas (Nymphaeaceae) es una familia con pocas especies y la mayoría de ellas son plantas acuáticas de agua dulce en lugares calmados y vulgarmente se conocen como nenúfares. Debido a que son plantas acuáticas, el nombre de la familia deriva de la palabra nympha del latín, ya que tienen cierta similitud con las ninfas, seres mitológicos con predilección por las aguas.

1024px-Rae_-_Water_Nymphs_(color)Ninfas acuáticas, se puede apreciar nenúfares a su alrededor (Pintado por Henrietta Rae, 1909).

Las ninfeáceas tienen su origen en regiones cálidas, pero actualmente son subcosmopolitas y se encuentran en muchas zonas del mundo, habitando estanques, lagos y cursos de agua dulce.

CARACTERÍSTICAS MORFOLÓGICAS

Los nenúfares son plantas acuáticas perennes, viven varios años, y rizomatosas, es decir, tienen un tallo engrosado debajo del suelo en el fondo del agua. En varias especies, vemos que algunas hojas son sumergidas y las otras flotantes en la superficie del agua, siendo a veces incluso membranosas (tienen los bordes levantados perpendicularmente hacia arriba para evitar la entrada de demasiada agua). Cuando presentan esta diferencia en el tipo de hojas hablamos de hojas heteromorfas, de diferente forma.

Flowering_victoriaHojas membranosas de nenúfar (Victoria amazonica) (Foto de Dirk van der Made).

Las flores son emergidas, crecen fuera del agua, y están constituidas por un nombre variable de sépalos, pétalos y estambres que nacen de manera helicoidal. Por lo tanto, son flores acíclicas, son asimétricas o irregulares porque no tienen ningún plano de simetría. Estas flores son solitarias, no nacen agrupadas, y a demás son hermafroditas, es decir, presentan órganos sexuales tanto masculinos (los estambres) como femenino (ovario) en la misma flor.

Nenufar-rosa Nymphaea tetragonaNenúfar venus (Nymphaea tetragona)(Foto de Miguel303xm).

Estas piezas del perianto (pétalos y sépalos) y los estambres son libres entre ellos, es decir, no están unidos o fusionados entre ellos, y normalmente se muestran en número elevado. Los estambres, a diferencia de muchos de otras flores, son laminares, similares a los pétalos. Por lo tanto, no son filamentosos, sino que tienen más grosor y son anchos.

DIVERSIDAD

Actualmente los géneros de nenúfares que tienen más relevancia son  Nuphar, Nymphaea y Victoria, pero también hay algunos más. A continuación presentaré algunas especies y casos bien interesantes.

El loto tigre nenúfar blanco egipcio (Nymphaea lotus) es originario de la valle del Nilo y de la África oriental. Es muy apreciado como ornamental y antiguamente los egipcios creían que la flor otorgaba fuerza y poder.

800px-Nymphaea_lotus4Nenúfar blanco egipcio(Nymphaea lotus) (Foto de Meneerke bloem).

El nenúfar amarillo (Nuphar lutea)  es típico de Europa, el norte de África y Oriente Medio y, como el anterior, también es muy ornamental. A demás, ha sido utilizado durante mucho tiempo en medicina tradicional. Sus raíces se aplicaban en la piel y se comía sus semillas y raíces para tratar diferentes enfermedades.

Nuphar_lutea_W160Nenúfar amarillo (Nuphar lutea) (Foto de Oksana Golovko).

Finalmente presentar al género Victoria, que es muy curioso por su tipo de polinización. Este tiene dos especies americanas, V. cruziana en Argentina y V. amazonica en el Amazonas y Brasil. Las plantas de este género son muy grandes, las hojas flotantes llegan a los 2 metros de diámetro y hacen flores vistosas de hasta 30 centímetros que se abren durante la tarde-noche. Cuando estas flores se abren desprenden fuertes olores y un pequeño calor, que junto con los colores blancos y amarillentos que tiene, resultan muy atractivas para los escarabajos o coleópteros (Coleoptera) que se alimentan de las extensiones de almidón que tienen las flores (cuerpos de almidón). Al amanecer siguiente las flores se cierran y capturan los escarabajos, haciendo que se impregnen de polen. Por la tarde de nuevo se vuelven a abrir y dejan escapar a los coleópteros. Entonces, como las flores ya han estado polinizadas varían a un color rosado y pierden el olor, dejando así que los escarabajos se sientan más atraídos por las flores blancas que aún han de ser polinizadas. Finalmente la flor rosada se sumerge.

V. cruziana & V. amazonicaA la izquierda, V. cruziana (Foto de Greenlamplady); A la derecha, V. amazonica (Foto de frank wouters).

IMPORTANCIA

Actualmente muchas especies son usadas como ornamentales, decorativas. A demás, las ninfeáceas también pueden ser utilizadas para extraer alimentos; las semillas y rizomas de los géneros Nymphaea y Victòria son comestibles. Por otro lado, una cosa bien curiosa es que los nervios de las hojas de algunas especies se han usado para extraer un líquido que sirve para curar mordiscos de víbora.

Espero que os haya cautivado la manera en que se comportan los nenúfares y todas las histórias y usos que llevan asociados, aunque ya solo por su belleza son cautivadores. Si te ha gustado no olvides compartir en las diferentes redes sociales. Gracias por tu interés.

REFERENCIAS

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