Diving beetle
| Dytiscidae | |
|---|---|
 |
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| Sunburst diving beetle Thermonectus marmoratus (Dytiscinae: Aciliini) inhabiting rock pool at Thiruvannamalai, India | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Superfamily: | Dytiscoidea |
| Family: |
Dytiscidae Leach, 1815 |
The Dytiscidae – based on the Greek dytikos (δυτικός), "able to dive" – are the predaceous diving beetles, a family of water beetles. They are about 25 mm (1.0 in) long on average, though much variation is seen between species. Dytiscus latissimus, the largest, can grow to 45 mm long. Most are dark brown, blackish, or dark olive in color with golden highlights in some subfamilies. They have short, but sharp mandibles. Immediately upon biting, they deliver digestive enzymes. The larvae are commonly known as water tigers. The family has not been comprehensively cataloged since 1920, but is estimated to include about 4,000 species in over 160 genera.
When still in larval form, the beetles vary in size from about 1 to 5 cm (0.5 to 2.0 in). The larval bodies are shaped like crescents, with the tail long and covered with thin hairs. Six legs protrude from along the thorax, which also sports the same thin hairs. The head is flat and square, with a pair of long, large pincers. When hunting, they cling to grasses or pieces of wood along the bottom, and hold perfectly still until prey passes by, then they lunge, trapping their soon-to-be-food between their front legs and biting down with their pincers. Their usual prey includes tadpoles and glassworms, among other smaller water-dwelling creatures.
As the larvae mature, they crawl from the water on the sturdy legs, and bury themselves in the mud for pupation. After about a week, or longer in some species, they emerge from the mud as adults.
Adult Dytiscidae, particular of the genus Cybister, are edible. Remnants of C. explanatus were found in prehistoric human coprolites in a Nevada cave, likely sourced from the Humboldt Sink. In Mexico, C. explanatus is eaten roasted and salted to accompany tacos. In Japan, C. japonicus has been used as food in certain regions such as Nagano prefecture. In the Guangdong Province of China, the latter species, as well as C. bengalensis, C. guerini, C. limbatus, C. sugillatus, C. tripunctatus, and probably also the well-known Great diving beetle (D. marginalis) are bred for human consumption, though as they are cumbersome to raise due to their carnivorous habit and have a fairly bland (though apparently not offensive) taste and little meat, this is decreasing. Dytiscidae are reportedly also eaten in Taiwan, Thailand, and New Guinea.
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Wikipedia