Cnideria feed in many different ways like predation, absorbing dissolved organic chemicals, filtering food particles out of the water, and getting nutrients from symbiotic algae within their cells. Most cnideria get food from predation.
Respiratory
Cnideria don't have any respiratory organs. Both cell layers absorb oxygen and expel carbon dioxide into the water. When water in the digestive cavity becomes stale, it has to be replaced and the nutrients that had not been absorbed yet are also expelled with it.
Circulation
Cnidaria don't have any organs or special tissues that are for circulation. They would get nutrients through diffusion.
Exertion
Gland cells in the gastroderm release enzymes that turn the food into a slurry. It circulates through the digestive cavity and throug connecting tunnels , so the gastroderm cells can absorb the nutrients. Absorbtion takes a few hours and digestion takes a few days. The nutrients circulate by water currents produced by cilia in the gastroderm or by muscular movements so the nutrients reach all parts of the digestive cavity. Nutrients reach the outer cell layer by diffusion. Indigestable remains of prey are expelled through the mouth. The main waste product of cells' eternal processes is ammonia which is removed by external and interanl water currents.
Response
Cnidaria have no brains or central nervous systems.Instead they have decentralized nerve nets consisting of sensory neurons that generate signals to respond to types of stimulus like odors, motor neurons that tells muscles to contract and cobwebs of intermediate neurons to connect them. Intermediate neurons also form ganglia that act as local coordination centers. The cilia of cnidocytes detect physical contact. Nerves inform cnidocytes when prey or attackers are detected. Most communication between nerve cells are through chemical synapses.
Movement
Adult cnidaria are either swimming medusae or sessile polyps. In medusae the only supporting structure is the mesoglea. Medusae swim by a form of jet propulsion. Hydras and some sea anemones move slowly over rocks.
Reproduction
Sexual reproduction involves a complex life cycle with noth polyp and medusa stages. All known cnidaria can reproduce asexually by various means in addition to being regenerated when fragmented.
Respiratory
Cnideria don't have any respiratory organs. Both cell layers absorb oxygen and expel carbon dioxide into the water. When water in the digestive cavity becomes stale, it has to be replaced and the nutrients that had not been absorbed yet are also expelled with it.
Circulation
Cnidaria don't have any organs or special tissues that are for circulation. They would get nutrients through diffusion.
Exertion
Gland cells in the gastroderm release enzymes that turn the food into a slurry. It circulates through the digestive cavity and throug connecting tunnels , so the gastroderm cells can absorb the nutrients. Absorbtion takes a few hours and digestion takes a few days. The nutrients circulate by water currents produced by cilia in the gastroderm or by muscular movements so the nutrients reach all parts of the digestive cavity. Nutrients reach the outer cell layer by diffusion. Indigestable remains of prey are expelled through the mouth. The main waste product of cells' eternal processes is ammonia which is removed by external and interanl water currents.
Response
Cnidaria have no brains or central nervous systems.Instead they have decentralized nerve nets consisting of sensory neurons that generate signals to respond to types of stimulus like odors, motor neurons that tells muscles to contract and cobwebs of intermediate neurons to connect them. Intermediate neurons also form ganglia that act as local coordination centers. The cilia of cnidocytes detect physical contact. Nerves inform cnidocytes when prey or attackers are detected. Most communication between nerve cells are through chemical synapses.
Movement
Adult cnidaria are either swimming medusae or sessile polyps. In medusae the only supporting structure is the mesoglea. Medusae swim by a form of jet propulsion. Hydras and some sea anemones move slowly over rocks.
Reproduction
Sexual reproduction involves a complex life cycle with noth polyp and medusa stages. All known cnidaria can reproduce asexually by various means in addition to being regenerated when fragmented.
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