Almost all are detrital and/or filter feeders.
When threatened many species squirt out noxious and sticky latex-like
threads which harden on contact with sea water, and entangle or irritate
the potential predator. These are extremely difficult to remove.
If this fails, they will eject their entire digestive system
(gut) in an attempt to scare the enemy and hence escape. The gut can
then be regenerated.
may harbour commensals inside their gut or respiratory system. Two
prominent ones are the eel-like pearl fish (Carapus) and the
pea crab (Pinnotheres).
Pentacta (length 6-8cm) is common on sandy/muddy areas. Phyllophorus
(up to 10crn) (both F. Cucumariidae), which prefers muddier substrates,
has been reported to be used to make a virtual "panacea" called "Air
Gamat". The animals are slit, their body fluids collected and then
left to stand for several weeks before sale.
Most famous of all is H. scabra, the Beche-de-Mer or Trepang
(F. Holothuridae) (length 15-20cm), a much sought after delicacy.
Degutted, cleaned and dried, they fetch good market prices. They prefer
The reef cucumbers (mostly F. Holothuridae) grow to larger sizes (length
up to 43cm). Their colours vary between brown and black, and are often
seen in large numbers in the lower littoral zone, usually, among Sargassum
covered rocks. Some of the reef species have been reported to contain
a poison called holothurin and should not be eaten.