| Photo Information |
Copyright: Marcello Romano (marcellr)
![Gold Star Critiquer/Silver Workshop Editor/Gold Note Writer [C: 208 W: 38 N: 1012]](http://i1.treknature.com/misc/g-s-g.gif) (3514) |
| Genre: Animals |
| Medium: Color |
| Date Taken: 2006-10-25 |
| Categories: Insects |
| Camera: Olympus C-7070 Wide Zoom |
| Exposure: f/3.2, 1/50 seconds |
| Photo Version: Original Version |
| Date Submitted: 2007-10-27 7:18 |
| Viewed: 703 |
| Points: 12 |
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| [Note Guidelines] Photographer's Note |
COLEOPTERA, DYTISCIDAE
Dytiscidae (predaceous water beetles) is one of the largest and most commonly encountered groups of aquatic beetles. Both adults and larvae are predaceous, and will attack a wide variety of small aquatic organisms. Although most species are small to medium sized, some adults can attain a length of 35 mm.
The family is estimated to include about 4,000 species in over 160 genera.
Dytiscids have a characteristic appearance (see this table), and can generally be recognized by having a hard, smooth, oval body, without any ventral spine, having the hind legs flattened and with a fringe of hairs so that it can act like a paddle, and having long, thin antennae. In the water, dytiscids swim by moving their hind legs simultaneously, like oars, while the similar appearing Hydrophilidae alternate the movement of their hind legs.
Dytiscids generally prefer slow moving or stagnant water, such as ponds, lakes, billabongs, dams, and pools at the edges of streams. They require atmospheric air, and the adult beetles go to the surface to gather air which they store in a chamber underneath their elytra (wing covers) to enable them to increase the time they can be submerged. Larvae lack this ability, but many species use a siphon in the form of long filaments at the end of the abdomen.
Adult dytiscids are capable of sustained flight, and often travel some distance to disperse and find new habitats. They generally fly in the evening or at night, and they use reflected light from a water surface as a method of finding a new habitat. They can be confused by artificial reflected surfaces (e.g. glass) or lights, and are often attracted to these sources rather than water.
Dytiscus semisulcatus (length: 24-30 mm.) is a freshwater species (with sulcate elytra in the female) usually confined to stagnant or almost stagnant water.
The species ranges over most Europe, and occurs as far east as Eastern asia. It has been found in North Africa and it is recorded from Majorca and Corsica.
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La macrofotografia consente di riprendere da vicino molte specie di insetti, e di mettere in evidenza i caratteri che permettono in seguito di identificarli, spesso anche a livello specifico.
Le nostre foto inevitabilmente privilegiano e rappresentano però solo alcuni gruppi, a discapito di altri.
I soggetti più facili da fotografare sono gli insetti volatori, specialmente quelli che frequentano i fiori per cercare nutrimento.
Seguono poi tutti gli altri insetti che si incontrano mentre si muovono sul terreno, sui tronchi e in altri ambienti allo scoperto.
Ma sono tagliate fuori ancora centinaia di specie che frequentano ambienti poco facilmente indagabili con le nostre attrezzature.
Fra questi ambienti, certamente uno è quello sommerso.
Mi riferisco ovviamente alle acque dolci, che presentano ecosistemi altrettanto complessi e vari di quelli terrestri.
Questi ambienti sono popolati da una miriade di forme viventi, soprattutto larve, ma anche insetti adulti, talvolta di notevoli dimensioni.
Ho tentato di fotografare alcuni di questi caratteristici insetti del Genere Dytiscus.
Quello che vi presento oggi è il Dytiscus semisulcatus.
Si tratta di una femmina, riconoscibile per le elitre solcate e i tarsi anteriori non dilatati a forma di ventosa, caratteristici del maschio.
Le foto sono state realizzate servendomi di un piccolo contenitore trasparente che ho portato con me per trasferire momentaneamente i coleotteri da fotografare. |
jrobertop, meyerd, Oz1, Silvio2006 has marked this note useful
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