Squilla empusa

Squilla empusa is reported from the eastern seaboard of the United States with a range extending from Cape Cod to the Gulf of Mexico. It is also reported from Brazil and the Mediterranean Sea. It lives in a U-shaped burrow in soft sediment on the seabed at depths from the intertidal zone down to about 150 m (500 ft).^[2]

The summer burrow of Squilla empusa consists of a tube with typically two openings connected by a horizontal tunnel some 15 to 50 cm (6 to 20 in) below the surface of the sediment. The horizontal section normally has two bends and a diameter of up to 10 cm (4 in), depending on the size of the occupant. In the more northerly parts of its range, this mantis shrimp excavates a vertical burrow in the winter up to 4.1 m (13 ft) deep. At this depth in the sediment, the oxygen content of the water decreases and the temperature rises. This behavioural adaptation may enable Squilla empusa to inhabit locations where the water temperature falls too low in winter for it otherwise to survive.^[4]

Two main methods of burrowing are employed. A vigorous fanning action of the pleopods causes particles of sediment to become suspended and the current produced pushes the plume backwards past the telson. Using this method, an animal can create a depression as large as itself within two minutes. It then turns round and use its maxillipeds to form a basket with which it carries lumps of sediment away from the excavation. This is a slower process but sustainable for a longer period. Further burrowing creates the typical tunnel with one or more openings, and this is frequently remodelled, often in the course of a few hours. Squilla empusa can dig to a depth of 20 cm (8 in) in less than an hour. When the animal is inside the burrow it sometimes uses its maxillipeds to create a current of water flowing through.^[5] This species is territorial and will defend its burrow from other mantis shrimps.^[2]

Squilla empusa is mainly nocturnal and feeds on fish, shrimps, crabs, krill, worms, molluscs and other mantis shrimps. The raptorial claws are unfolded with great rapidity to spear, slash and immobilise the prey, which is brought back inside the burrow when caught.^[2]