Echinoderm- Echinoderms come from the phylum, Echinodermata. Echinoderms are sea creatures, typical bottom feeders on the sea floor. This phylum consists of animals such as starfish, sea urchins, sea lilies, sea cucumbers, and more. Most echinoderms are classified by their symmetric, pointed bodies.
Starfish: the Starfish's excretory system is similar to that of a human's, other than starfish not having any excretory organs. Without excretory organs, starfish are still able to get rid of their waste, not quite like humans. They are capable of excreting waste from their anus and they release liquid nitrogenous waste, or urine as well. Once a starfish's food is digested it passes from the stomach and passes down through the anus. A starfish releases its urine through its foot tubes found one of the ends of the starfish. Unlike spit glands in human's starfish have digestive glands that forms the waste to be removed from the body. Starfish urinate like humans and unlike other organisms because they are sea creatures. As sea creatures, they receive more than enough water than needed for their body, so they are capable of releasing more water from the body. Usually, organisms release their waste but retain the water due to the scarcity of water that they receive in their lifetime.
Sea Urchins: Sea urchins surprisingly have an excretory system just like all other echinoderms. By the look of a sea urchin, it would not seem likely. However, like starfish and other echinoderms, sea urchins just like the one shown, and many others alike, have tube feet. Tube feet are the organs that release nitrogenous waste out of the sea urchins. The tube feet on the sea urchin are usually along the spinal cords. Also, on most sea urchins, there are more than just one tube foot. Normally, there are five or more tube feet on the body of a sea urchin. Sea urchins only have tube feet because of the amount of water it absorbs in its life. the ecosystem of a sea urchin is usually on the sea floor deep in the bottom of the sea. So excreting nitrogenous waste is a sea urchins way of releasing extra water from the organisms body.
Sea Slug: the excretory system of a sea slug is very simple. They have a diet of planktons and other miniscule organisms deep on the ocean floor, so their digestive system and excretory system is very simple. Their food is digested from the oesophagus, but surprisingly it is does not pass through the digestive gland in its body like most other organisms. The waste from the then the extra waste in the sea slugs body is removed from the anus, even if the waste was not from the food that the sea slud has digested. The waste that is removed from the body is removed in tiny pellets that have travelled from the intestine to the anus.