The pictured rove beetle (''Thinopinus pictus'') is a wingless

rove beetle The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...

which lives on the sandy beaches of the

West Coast of the United States The West Coast of the United States, also known as the Pacific Coast, Pacific states, and the western seaboard, is the coastline along which the Western United States meets the North Pacific Ocean. The term typically refers to the contiguous U.S ...

from southern

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

. It is nocturnal, emerging at night from temporary sand burrows to feed on beach hoppers ('' Orchestoidea'').

Identification

Like other

s, ''T. pictus'' has shortened

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

, so that most of its

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

is exposed. Males average , females average . Males possess a cleft in the last abdominal sternite, which makes them readily discernible from females. Their cryptic coloration varies geographically in response to lighter colored sand in the southern part of their range. Populations north of central

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

tend to be darker in response to the dark volcanic sand, while those in the southern range are quite pale. Because of this variation, ''T. pictus'' was once thought to be made up of two subspecies.

Ecology

''T. pictus'' inhabits the sandy intertidal zone; during the day, they hide in temporary sand burrows or under kelp and beach debris with a preference to inhabit the wettest and softest sand available. At night they emerge and move to the high tide level to find prey. Individuals switch between inactive ambush predation and active foraging for their prey, which consists mostly of beach hoppers ( Amphipoda). They have also been observed eating beach flies,

isopods Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and ...

, and other ''T. pictus''. Males seem to feed less than females, but are more active than females, possibly to increase the chance of finding a mate.

Reproduction

The breeding season is thought to be from August to October. Dissected females have been shown to carry only 2–3 eggs, which are oviposited singly in the sand. These beetles likely have long lifespans in order to reproduce sufficiently. In the laboratory, eggs hatch at about 14 days.

Larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e are whitish with black markings. The duration of their instars is unknown.

References

External links

*http://bugguide.net/node/view/321754 * {{Taxonbar, from=Q7191211 Staphylininae Beetles described in 1852 Beetles of North America Wingless beetles