Basic Information on the Sea Cucumber -Holothuria pardalis
All sea cucumbers are ocean dwellers, though some inhabit the shallows and others live in the deep ocean. They live on or near the ocean floor—sometimes partially buried beneath it. Sea cucumbers feed on tiny particles like algae, minute aquatic animals, or waste materials, which they gather in with 8 to 30 tube feet that look like tentacles surrounding their mouths. The animals break down these particles into even smaller pieces, which become fodder for bacteria, and thus recycle them back into the ocean ecosystem. Earthworms perform a similar function in terrestrial ecosystems. Sea cucumbers, particularly eggs and young larvae, are prey for fish and other marine animals. They are also enjoyed by humans, especially in Asia, and some species are farmed as delicacies. When threatened, some sea cucumbers discharge sticky threads to ensnare their enemies. Others can mutilate their own bodies as a defense mechanism. They violently contract their muscles and jettison some of their internal organs out of their anus. The missing body parts are quickly regenerated.
The nervous system of the Sea Cucumber -HOLOTHURIA PARDALIS
The sea cucumber has no true brain, but a ring of neural tissue surrounds the oral cavity and sends nerves to the tentacles and the pharanx. If the nerve ring is removed, it can still walk and move. Their enteric nervous system innervates the regeneration of their guts as seen in the video, they spit out for protection. The main components of the ENS were divided depending on their location within the mesothelial layer, the connective tissue and the luminal layer. In the mesothelium they found a fiber network within the muscle layer that innervates the visceral muscle. There is a second mesothelial plexus formed by large nerve bundles that run along the longitudinal axis of the gut, and mostly parallel to the longitudinal muscle fibers. Within the connective tissue there are thick fibers that would correspond to nerves connecting the mesothelial plexus with the connective and luminal layers. There is also a network of small neurons and fine fibers all throughout this connective layer. Finally, the luminal plexus is formed by neuroendocrine-like cells distributed among the luminal epithelial cells. Occasionally, some of these cells display fiber projections extending towards the mesothelium.