Ecology and behavior Steller's sea cow

illustrations of dentition of steller s sea cow johann christian daniel von schreber

whether steller s sea cow had natural predators unknown. may have been hunted killer whales , sharks, though buoyancy may have made difficult killer whales drown, , rocky kelp forests in sea cow lived may have deterred sharks. according steller, adults guarded young predators.

steller described ectoparasite on sea cows similar whale louse (cyamus ovalis), parasite remains unidentified due host s extinction , loss of original specimens collected steller. first formally described sirenocyamus rhytinae in 1846 johann friedrich von brandt. species of cyamid amphipod reported inhabiting sirenian. steller identified endoparasite on sea cows, ascarid nematode.

like other sirenians, steller s sea cow obligate herbivore , spent of day feeding, lifting head every 4 5 minutes breathing. kelp main food source, making algivore. sea cow fed on several species of kelp, have been identified as: agarum spp., alaria praelonga, halosaccion glandiforme, laminaria saccharina, nereocyctis luetkeana , thalassiophyllum clathrus. steller s sea cow fed directly on soft parts of kelp, caused tougher stem , holdfast wash on shore in heaps. sea cow may have fed on seagrass, plant not common enough support viable population , not have been sea cow s primary food source. further, available seagrasses in sea cow s range (phyllospadix spp. , zostera marina) may have grown deep underwater or been tough animal consume. since sea cow floated, fed on canopy kelp, believed have had access food no deeper 1 meter (3.3 ft) below tide. kelp releases chemical deterrent protect grazing, canopy kelp releases lower concentration of chemical, allowing sea cow graze safely. steller noted sea cow grew thin during frigid winters, indicating period of fasting due low kelp growth. fossils of pleistocene aleutian island sea cow populations larger commander islands, indicating growth of commander island sea cows may have been stunted due less favorable habitat , less food warmer aleutian islands.

steller described sea cow being highly social (gregarious). sea cow lived in small family groups , helped injured members, , apparently monogamous. steller s sea cow may have exhibited parental care, , young kept @ front of herd protection against predators. steller reported female being captured, group of other sea cows attacked hunting boat ramming , rocking it, , after hunt, mate followed boat shore, after captured animal had died. mating season occurred in spring , gestation took little on year, calves delivered in autumn, steller observed greater number of calves in autumn @ other time of year. since female sea cows had 1 set of mammary glands, had 1 calf @ time.

the sea cow used forelimbs swimming, feeding, walking in shallow water, defending itself, , holding on partner during copulation. according steller, forelimbs used anchor sea cow down prevent being swept away strong nearshore waves. while grazing, sea cow progressed moving tail (fluke) side side; more rapid movement achieved strong vertical beating of tail. slept on backs after feeding. according steller, sea cow mute , made heavy breathing sounds, raspy snorting similar horse, , sighs.