Nepidae

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Nepidae

Nepa cinerea

Scientific classification

Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hemiptera
Suborder:	Heteroptera
Family:	Nepidae

Genera

Nepa
Ranatra

Nepidae is a family of insects in the order Hemiptera, suborder Heteroptera. Sometimes it is placed in the infraorder Nepomorpha.[1] They are commonly called water scorpions for their superficial resemblance to a scorpion, which is due to the modification of the legs of the anterior pair for prehension, and to the presence of a long slender process, simulating a tail, at the posterior end of the abdomen. There are two genera in the family, Nepa and Ranatra. Members of the Ranatra are sometimes called needle bugs or water stick insects as they are more slender than Nepa. The common British species (Nepa cinerea) lives in ponds and stagnant water, and feeds upon aquatic animal organisms principally of the insect kind. Respiration in the adult is effected by means of the caudal process, which consists of a pair of half-tubes capable of being locked together to form a siphon by means of which air is conducted to the tracheae at the apex of the abdomen when the tip of the tube is thrust above the surface of the water. In immature forms the siphon is undeveloped and breathing takes place through six pairs of abdominal spiracles. The eggs, laid in the stems of plants, are supplied with seven filamentous processes which float freely in the water.

In Nepa the body is broad and flat; but in an allied water-bug, Ranatra, which contains a single British species (R. linearis), it is long and narrow, while the legs are very slender and elongate. Certain members of this group, sometimes erroneously referred to the Nepidae, but really forming a separate family, Belostomatidae (giant water bugs), are of large size, a South American species, Belostoma grande, reaching a length of between 4 and 5 in.

[edit] Ancient super-scorpions

In December 2005, scientists reported finding prehistoric footprints in Scotland of a water scorpion which was as large as a human being. Tracks found in rocks, made 330 million years ago by a six-legged Hibbertopterus water scorpion, indicate the creature measured more than five feet long and over three feet wide. Notwithstanding its formidable size, the large water scorpion would not have presented a threat to other creatures of its size.[2]