Little Skate - Biology and Ecology

Biology and Ecology

Little skates are more active at night and spend much of the day buried in sediment, usually near specific landscape features such as depressions excavated by other animals. They employ a curious mode of locomotion, dubbed "punting" by the first scientists to document it, to move over the sea floor. The forward lobes of the pelvic fins are modified into leg-like structures called "crura" (singular "crus"), containing three flexible joints and modified skeletal and muscular elements. The little skate pushes off the substrate with both crura and then glides a short distance on its wings while repositioning the crura for the next push. The crura are also used as pivots when the skate needs to turn. It has been speculated that using the pelvic fins in this manner assists in hunting, by reducing water turbulence that might alert the prey or distort the ray's electroreception.

The tail of the little skate contains an electric organ that intermittently generates a weak electric field (the electric organ discharge or EOD). The EOD lasts 70 ms and has a head-negative monophasic waveform. This electric organ is thought to function in communication, and may help potential mates locate one another.

Young and adult little skates are preyed upon by sharks, other skates, teleost fishes (including cod, goosefish, sea ravens, longhorn sculpins, bluefish, and summer flounders), gray seals, and rock crabs (Cancer irroratus). Their egg cases are preyed on by the sea urchin Strongylocentrotus droebachiensis and the whelk Buccinum undatum. Known parasites of the little skate include the protozoans Caliperia brevipes, Haemogregarina delagei, and Trypanosoma rajae, the myxosporeans Chloromyxum leydigi and Leptotheca agilis, the nematode Pseudanisakis tricupola, and the copepods Eudactylina corrugata and Lernaeopodina longimana.