1. Class: Holothuroidea
Sea Cucumbers

2. General Information
Pickle-shaped animals with feathery tentacles on one end
Large range of sizes (some the few centimeters; some species can be over a meter)
Large range of habitats – shorelines to the abyssal plains
Most stay attached to the floor, very few species swim
The muscular walls are eaten in many countries

3. Feeding & Digestion
Cucumbers have a mouth at one end, a long tube going down the center and an anus at the other end
Mouth
Ringed by tentacles (modified tube feet)
Some species use the tentacles to take in sediment
Some species can extend their tentacles to catch passing food particles
Digestive tube
Contains a stomach and a long, thin, coiled intestine

4. Skeleton & Muscles
They have no ossicles or large plates to give them a rigid skeleton
How are they classfied as echinoderms?
They have microscopic spicules embedded in their skin
These spicules vary from species to species so they are a useful identification tool
Muscles
Located in the body wall
Developed enough for locomotion
This is the part that is eaten

5. Respiration Respiratory Tree
An internal structure that attaches to the intestine
Seawater is “inhaled” through the anal opening and fills the branches of he tree
Body fluid absorb the oxygen and the waste water is “exhaled” back through the anal opening
Sometimes small crabs and fish invade the respiratory tree and set up residence
They don’t hurt the host, but they benefit from the situation
What’s this called?
Commensalism

6. Protection Cuverian tubules Evisceration
Specialized branches of the respiratory tree that resemble long, slender threads
These threads are sticky and sometimes contain toxic chemicals
When ejected, they entangle the offending organism
Evisceration
Some species can forcibly eject their internal organs out of the anal opening
This can happen if they are handled roughly, encounter warm or stagnant water
Under favorable conditions the organs regenerate and the cucumber carries on