''Aepus marinus'' is a species of

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

in the family

Carabidae Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it is one of the 10 most species-rich animal fami ...

. It is found in the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

of marine habitats in northwestern Europe where it lives in crevices and under stones. The adult beetle is about in length, and is a reddish-yellow colour.

Description

''Aepus marinus'' is a very small beetle, with adults reaching a length of about . The head is relatively large while the thorax is rather small and shaped like an isosceles triangle, with the base at the front and the apex at the rear. There is a deep furrow in the centre of the dorsal surface of the thorax. The

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 ...

are narrowed at the front and shorter than the abdomen, and are sculptured with indistinct short striae (narrow grooves or channels) and puncture marks. The legs are long, as are the antennae, which are shaped like a string of beads.

Distribution and habitat

The species is found throughout northwestern Europe, in countries such as

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

and

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

. It is only found in marine habitats, on beaches between the middle of the

and the extreme high water mark reached by spring tides. It lives beneath overhangs, in rock crevices and under stones embedded in clayey gravels and sands along the coastline, as well as occasionally in

driftwood __NOTOC__ Driftwood is wood that has been washed onto a shore or beach of a sea, lake, or river by the action of winds, tides or waves. In some waterfront areas, driftwood is a major nuisance. However, the driftwood provides shelter and fo ...

washed up at the tideline. Little light penetrates the locations where it is found and the eyes are rudimentary. It is most common high up the beach, and always above the ''

Fucus ''Fucus'' is a genus of brown algae found in the intertidal zones of rocky seashores almost throughout the world. Description and life cycle The thallus is perennial with an irregular or disc-shaped holdfast or with haptera. The erect portion o ...

'' zone, being mostly replaced lower down the beach by the closely related '' Aepus robini''. In France, where it is known from a few locations in Brittany and Normandy, it has been found to be largely restricted to a strip a couple of metres wide bordering the upper limit of the spring tides.

Ecology

''Aepus marinus'' is a

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

, feeding on small

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

s such as

springtail Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). Although the three orders are sometimes grouped together in a class called Ento ...

s. When the tide rises it retreats into pockets of air in crevices and under stones, emerging to forage when the water retreats. It can carry a bubble of air under its elytra enabling it to breathe when under water, and its adaptations enable it to recover more quickly after submergence than ''A. robini''. It is active all year round, but the breeding period is probably between about April to September.

References

{{Taxonbar, from=Q25991 Beetles described in 1783 Trechinae Beetles of Europe Taxa named by Hans Strøm