Benthodytes sanguinolenta Théel, 1882, Sea Cucumber

General Description

Body soft, gelatinous, elongated, dorsoventrally flattened, slightly convex or arched dorsally; typically purple-violet to red in colour with residual red and darker processes visible in preserved specimens; fused lateral tube-feet create a distinct brim, flattened and wide anteriorly; mouth ventral but not terminal, oral papillae present; anus dorsal and almost terminal; body wall usually thin (can be transparent), pliable; 18-20 tentacles with soft, flattened discs circled by small digitiform processes; brim tube feet in single row, mid-ventral tube feet mixed paired series sometimes grey-black; two scattered bands of retractable dorsal papillae, sometimes only visible as dots, water-vascular canals often visible as dark lines, bare dorsal inter-ambulacrum; ossicles rare spinous rods, but often dissolved or not detected; up to ~35 cm long

Biology

As a benthic deposit feeder Benthodytes sanguinolenta spends most of its adult life crawling along the seafloor feeding on organic particles that have fallen from above. It is also capable of swimming and has been seen doing so in ROV (Remotely Operated underwater Vehicle) footage, e.g. from Ningaloo off the coast off Western Australia. It swims by undulating its widened brim and by flexing its body back and forth. As with most benthic sea cucumbers, adult swimming in Benthodytes sanguinolenta is thought to be facultative - i.e. only used when needed.

Benthodytes sanguinolenta was first collected in 1875 during the historic HMS Challenger expedition from stations at over 2000 m and over 4000 m in the South Pacific Ocean off South America. It has since been found in oceans worldwide, typically at depths of ~700-7000 m on sandy or muddy bottoms. In Australia this species is currently known from the deep sea off Western Australia, Queensland, New South Wales, Victoria, South Australia, and Tasmania.

Distribution

Worldwide at depths of 768-7250 m. In Australia currently recorded from deep sea off Western Australia, Queensland, New South Wales, Victoria, South Australia, and Tasmania.

Habitat

Deep sea marine benthic species occurring worldwide from bathyal to hadal depths (768-7250m).