CNIDARIA
Cnidarians lack a circulatory system. they don't require one because all the cells of cnidaria are in contact with the water. the water contains all of the oxygen and nutrients the simple animal needs. A circulatory system is not necessary for cnidarians because there are no cells that need oxygen and nutrients delivered to them.
Jellyfish- Jellyfish have no specialized circulatory system. Oxygen is usually absorbed to through their thin bodies. They are a very deadly sea creatures that emit a shock to stun or even kill prey. Some jellyfish's electrical shock is so strong that it can kill a human. Their tentacles can grow up to hundreds of feet on some species.
Coral- Coral can come in many different colors and sizes. They also have no real circulatory system. Coral provided protection to some other sea creatures and give them a place to live.
Sea Anemones- Sea anemones use their tentacles to catch food. The anemone moves all the nearby tentacles around the creature to hold and sting it before moving the creature towards the mouth. The sting capsule or nematocyst, in the tentacles contains a coiled, hollow filament that is usually barbed and contains poison. Sea anemones are carnivores. They gain most of their energy from the sunlight.
Coral- Coral can come in many different colors and sizes. They also have no real circulatory system. Coral provided protection to some other sea creatures and give them a place to live.
Sea Anemones- Sea anemones use their tentacles to catch food. The anemone moves all the nearby tentacles around the creature to hold and sting it before moving the creature towards the mouth. The sting capsule or nematocyst, in the tentacles contains a coiled, hollow filament that is usually barbed and contains poison. Sea anemones are carnivores. They gain most of their energy from the sunlight.