Description of family
Echinoderms usually have radial symmetry. They have a few arms usually 5 or more that are group two on the left one in the middle and two on the right. Their body are made up of five equal segments which contain duplicates of different internal organs. Echinoderms do not have a heart, a brain or eyes. Their mouths are located on the under side and their anus is located on top although this does not occur with feather star, sea cucumbers and some urchins. Echinoderms also have tentacle like things know as ambulacral feet or tube feet. These tube feet have suction pads at the very tips of them and are hydraulically controlled by the vascular system. The vascular system supplies water via small to the tube feet so when the tube feet press against an object the water is removed and a suction affect occurs. When the water returns suction is lost. This allows echinoderms to move very slowly.
Classification
Unlike most echinoderms sea cucumber don’t have strong radial symmetry but they have a distinct top and bottom. As the name suggests sea cucumbers are cucumber shaped with muscular, flexible body with their mouth at one end and their anus at the other. Around the mouth they have tentacles some what like tube feet these are used in food collecting. And their size rages from only about a few centimeters to meters.
Feeding habits
Almost all sea cucumber feed on the organic material coating sandy areas. They move over the ground eating then sand then when the sand passing through their digestive track the organic matter (Plankton, bacteria) is extracted and the sand is removed via the anus. Another way some sea cucumbers feed extending their feeding tentacles outward this allows them to catch different partials floating by.
Habitat
Sea cucumbers are found in almost all marine environments but they are more likely to be found on tropical shallow-water coral reefs. Although they are usually found in shallow water there are sea cucumbers living in the bottom of oceanic trenches up to 3.5 kilometers deep. Sea cucumbers only avoid areas which have lots of waves. Also they are found on all types of surfaces ranging from muddy sand to bedrock.
Predators / Defense mechanisms
The sea cucumbers don’t have any specific predator but is usually eaten by fish large then it and sea stars. When attacked by one of there predators the sea cucumber shoots out a sticky thread like structure which is actually parts of their guts. As well as being toxic these threads trap the predator allowing the sea cucumber to get away. These thread like structures quickly regenerate. Other species of sea cucumber are able to remove parts of its body and shoot them towards the predator. The sea cucumber does this by violently contracting their muscles causing their internal organs to be released through their anus. This distracts the predator from attacking the sea cucumber again allowing it to get away. And much like the threads the organs regenerate quickly.
Symbiotic relationships
The sea cucumber has a few different symbiotic relationships one is with tiny polychaete worms that look almost identical to the skin of the sea cucumbers. They crawl across the skin and cleaning the surface of the sea cucumber in return for getting a place to live. Another relationship the sea cucumber has is with pearl fish which lives inside their anus during the day and leaves the sea cucumber at night to feed. When the pearl fish tries to enter the body of the sea cucumber the sea cucumber closes its anus but because the sea cucumbers breathe through their anus it must eventually open and when it does the pearl fish swims in. The reason the sea cucumber does not want the pearl fish inside it is because the pearl fish is parasitic and it feeds on the gonads of sea cucumbers.
If the sea cucumber became extinct
If sea cucumber became extinct there would be a large increase in the amount of algae in the ocean which would make it a lot harder for the coral to get energy from the sun. Because of this the coral would begin to die causing the whole of the coral reef ecosystem would be begin to collapse. Also all of the sea cucumbers predators would have a limited food source so you would see a decrease in the population of the leather back sea turtle and we would also the almost extinction of the Perl fish.
The sea cucumbers role in the ecosystem
Sea cucumbers have a very large role in the ecosystem first of all they eat the algae which helps to promote more coral growth and stop the coral dying. They also provide a good food source for there predators which include the leather back sea turtle and a collection of fish larger then it. Another way the sea cucumber gives back to the ecosystem is by unwilling providing shelter and protection from the Perl fish. More importantly the sea cucumber helps to look after and protect the whole of the coral reef ecosystem from global warming they do this because when they ingest sand the natural digestive processes in the sea cucumbers gut increases the pH levels of the water on the reef where they defecate and this reduce the impact of ocean acidification due to global warming.
How will global warming affect sea cucumbers
Global warming will affect sea cucumber a lot better then most other animals in the ecosystem. Because of global warming they will be an increase in the amount of algae and so the sea cucumber will have more food and in a small amount of time their population will increase which in turn will increase the population of their predators because the will have a larger amount of food and so eventually you will end up with end up with a larger amount of animals in each level of the food chain and a larger population of animals in the ecosystem over all.
The sea cucumber in a food web
The sea cucumber in a food chain
References / Sources
http://en.wikipedia.org/wiki/Sea_cucumber
http://en.wikipedia.org/wiki/Sea_cucumber_(food)
http://animals.nationalgeographic.com.au/animals/invertebrates/sea-cucumber/
http://www.reefed.edu.au/home/explorer/animals/marine_invertebrates/echinoderms/sea_cucumbers
http://www.reef.edu.au/asp_pages/secb.asp?FormNo=46
http://www.australiangeographic.com.au/journal/sea-cucumber-poo-could-save-great-barrier-reef-ocean-acidification-coral-one-tree-island.htm