Arxiu d'etiquetes: Coleoptera

Flying made insects more diverse

The appearance of insect wings represented an adaptive improvement in the evolutionary history of these organisms, since they allowed them to spread and diversify across all kind of habitats. It is precisely for these events that wings are very diverse organs which have undergone a lot of changes.

In the following article, I will talk about the appearance of wings as elements that have ensured the diversification of insects, and also about the evolution of these organs and about their subsequent changes.


Insects form the most diverse and successful group among the current fauna, and they’re also the unique invertebrates capable to fly. Even though they almost haven’t change since their appearance during the Devonian era (395-345Ma), the appearance of wings and of the ability to fly (alongside with other events that took place at the same time) allowed them to diversify rapidly.

Timeline of geological eras. Hexapoda and also insects appeared during the Devonian era (Picture from

Nowadays, there are almost 1 million of species of insects identified, and it’s known that there are lots of them waiting to be identified.

When winged insects appeared?

As you probably know, not all insects worldwide have wings: there are apterous insects (that is, insects without wings), which form the Apterygota group, and winged insects or Pterygota (is interesting to say that some organisms of this group have lost their wings later).

The most ancient winged insect is probably Delitzchala bitterfeldensis, an organism from the Palaeodictyoptera group dated from early Carboniferous in Germany (50Ma after the appearance of insects during the Devonian era, more or less).

Approximated representation of a Palaeodictyoptera. In contrast with current insects, these ones had three pair of wings instead of only one or two (the first one was probably a couple of little lobes located near the head) (Picture from Zoological excursions on Lake Baikal).

However, the fossil remains of the most ancient insect known nowadays, Rhyniognatha hirsti (dated from the early Devonian in Scotland, which was found in the “Rhynie Chert” sedimentary deposit), which has no wings, reveal that this insect shares some traits with winged insects (Pterygota). According to this, the origin of insect wings could be more ancient (probably from the Devonian or even more ancient).

We are still far from knowing the exact moment when the appearance of winged insects took place. But, despite of this, we can affirm that the ability to fly allowed them to reach new habitats, looking for more and better food and also run away from predators more easily. These events have provided a huge evolutionary advantage to insects and allowed them to diversify.

How did wings appeared?

Discrepancies toward the origin and evolution of insect wings is not limited only to “when ” , but also “how”: How did they appeared? Which structures from ancient insects have been modified to become wings?

There exist 4 hypothesis that try to explain the way wings were formed from different ancient organs: branchial hypothesis, stigmatic hypothesis, parapodial hypothesis and paranotal hypothesis.

First of all, and in order to understand all these hypothesis way better, we need to know the basis of corporal structure of insects. Let’s see the body scheme of a cricket (Orhoptera order):

Body scheme of a generic insect. There are 3 principal segments: 1) Head, where central nervous system and feeding functions are located, 2) Thorax, which has a locomotor function (here we can find all the appendices, including wings in winged insects); it’s divided in three parts: prothorax, mesothorax and metathorax; 3) Abdomen, in this segment we can usually find all the visceral organs. Moreover, we can also find the spiraculi located at both soft sides of its body, that is, holes that connect with the tracheal system and through where the exchange of gases takes place (Picture from Asturnatura).


Representation of the tracheal or respiratory system of an insect. This system is branched into the organism (Picture by M. Readey, Creative Commons).


So now, which are these hypothesis?

1) Branchial hypothesis 

According to this hypothesis, ancient Pterygota insects were aquatic organisms that were derived from terrestrial insects that got adapted to live underwater. Those ancestors breathed, as current insects, through spiracles connected to a net of internal pipes or tracheas. During the adaptation process to aquatic environment, these insects developed branchial or gill sheets on those spiracles in order to breathe underwater. Then, when they migrated back from aquatic to terrestrial environment, these sheets lost their ancient function and became a kind of wings.

According to recent data, it’s considered one of the most plausible hypothesis.

2) Stigmatic hypothesis

In the thoracic region, that is, where legs and wings born, the respiratory spiracles tend to be closed. According to this hypothesis, wings could be tracheal pipes expeled to the outside of the body in the thoracic region.

3) Parapodial hypothesis

This is a very simple hypothesis: it tells us that wings were formed by modified legs.

4) Paranotal hypothesis

A few years ago it was considered the most  plausible hypothesis, but now it competes with the brancial hypothesis. This is the most accepted hypothesis about the origin of insect’s wings. According to this hypothesis, wings were formed by the expansions of the tegumentary membrane located at both sides of the body, that is, the space located between the dorsal and the ventral surface of the body.

The expansions are known as “paranotes” (these structures gave the name to the paranotal hypothesis).

Ancient vs modern: Paleoptera and Neoptera

Nowadays, mostly of insects presents only one or two pairs of wings located, respectively, in the mesothorax and in the metathorax (middle and posterior segments), and not three pairs, as ancient insects usually had.

The way the two pairs of wings are articulated with the thorax, together with their position, allow us to differentiate two main groups of winged insects or Pterygota: Paleoptera and Neoptera.


Generally, the Paleoptera insects can’t fold up the wings over the abdomen (this is an ancient condition). Moreover, the two pairs of wings are similar both in size and function, and also in the disposition of the veins that travel under their surface. Inside this group we find organisms from the Ephemeroptera order (for more information, take a look to my article about bioindicators), from Odonata order and also from the Palaeodictyoptera group, now extinguished.

An specimen of Odonata with its four wings unfolded because it has no way to fold up them over the abdomen (Picture by Ana_Cotta on Flickr, Creative Commons).


This group contain the rest of winged insects. Contrary to the ones explained above, Neoptera insects possess articulations that allow them to fold up the wings over the abdomen. Moreover, their wings are not always equal , and they can develop another functions (and new ones as well).

The wings of many groups of Neoptera insects have undergone a lot of secondary modifications, which allowed flying insects to diversify even more. Next, I will talk you about these secondary modifications.

An specimen of Diptera with its wings folded over its abdomen thanks to their articulations (Picture by Sander van der Wel on Flickr, Creative Commons).

Secondary modification of Neoptera’s wings

Generally, one of the two pairs of wings assumes the flying function (the ‘main wings’) while the other pair subordinates to the main one. This subordination can be expressed in two ways: 1) without external modifications (the subordinated pair of wings is limited to assist the main pair during the flight), 2) with secondary modifications, so the modified wings assume a new function.

Some Neoptera insects have undergone drastic modifications in one of the two pairs of wings. Let’s see some examples:

COLEOPTERA (beetles): the forewings, known as elytra, are a very hard structures that protect the rest of the body when they’re folded up. In this case, the hind wings are the main ones, so they assume the function of flying.

An specimen of a longhorn coleopter taking off. In this picture we can appreciate the forewings transformed into elytrum and the hind ones assuming the flying function (Picture by Matthew Fang on Flickr, Creative Commons).

HETEROPTERA (greenflies, cicadas, bedbugs): the forewings, known as hemelytra, aren’t completely hardened as in the case of beetles: only de proximal part is hardened, while the distal part has a membrane texture.

An specimen of Kleidocerys reseda (Picture by Mick Talbot on Flickr, Creative Commons).

POLINEOPTERA: in both cases that I’ve explained above, the hardening process of the forewings entails the loss of their veins; in Polineoptera insects (for example, cockroaches), the forewings are harder than the hind ones, but they retain their veins.

An specimen of Periplaneta americana (american cockroach). Its wings are plenty of veins (Picture by Gary Alpert, Creative Commons).

DIPTERA and HIMENOPTERA (flies and mosquitoes; wasps, bees and ants): in this case, the forewings assume the flying function; on the other hand, the hind wings get reduced or modified, and sometimes they don’t appear. The hind wings of flies became equilibrium organs, the halteres.

An specimen of crane fly (Tipulidae). The halteres (red circle) are located behind the forewings (Public domain picture).

ALTRES MODIFICACIONS: we can also talk about the changes in the shape, color, presence of filaments or scales, or even about the variations according to sex, hierarchy or geography location (for example, thats the case of ants or termites).

.              .             .

The origin and evolution of insect wings is still a fact waiting to be solved. Even so, independently of the moment and the way this event took place, is undeniable that wings have become key organs for the evolution and diversification of insects.


Top picture by USGS Bee Inventory and Monitoring Lab (Creative Commons).


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.


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.


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.


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).


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.


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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.


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.


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.


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).


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.


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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.


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.


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.


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).


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.


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