Cnidaria+-+Simon

 __ Cnidaria __ **Kingdom:** Animalia **Phylum:** Cnidaria **Classes:** __Anthozoa__, Medusozoa, __Cubozoa__, __Hydrozoa__, __Scyphozoa__, Staurozoa, Myxozoa, Polypodiozoa (The underlined ones are the four major classes) 

**Body Plan:** The basic body plan of Cnidarian is a sac with a central digestive compartment, the gastrovascular cavity. There are two forms, a polypoid form and a medusoid form. The polyp form is a tubular body with the mouth directed upwards. The medusa form is umbrella shaped with the mouth directed downwards. **Germ Layers:** Cnidaria are diploboastic, which means they have two main cell layers, the ectoderm (epidermis) and the endoderm (gastrodermis). **Symmetry:** Cnidaria are radially symmetrical with body parts radiating from a central axis. **Coelomate:** Cnidaria are acoelomate. (They do not contain a coelom.)

**Habitat:** Cnidaria live in aquatic environments and inhabit all depths from the sandy substrate, up to the surface. **Movement:** Medusae swim by a form of jet propulsion. Hydras move by crawling or somersaulting. Both involve the nerve net, and how stimulus in one part of the organism will spread across the whole body via the nerve network. **Skeletal System:** Medusae have a layer of mesoglea (jelly-like substance) between their germ layers, which acts as a supporting structure.

**Evolutionary Advancement:** A big evolutionary advancement is the extracellular digestion of food. Cnidaria also have cnidocytes (nematocytes) which are venomous cells that help them catch their prey and protect them from predators.

**Special Adaptations:** Cnidaria have special body structures that have a layer of jelly in between the two skin layers that allows them to move easily through the water. They have nematocytes that allow them to stun, kill, and paralyze their enemies. These nematocytes fire toxins into predators/prey that touch the Cnidaria. (We get "stung.")

**Feeding Patterns:** Cnidaria feed through predation, absorbing dissolved organic chemicals, filtering food particles out of the water, and obtaining nutrients from symbiotic algae within their cells.

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">**Respiration:** Cnidaria have no respiratory organs, its cell layers absorb oxygen from the water and expel carbon dioxide the same way.

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">**Circulation:** Cnidaria have no circulatory organs.

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">**Excretory:** Cnidaria expel its waste through its mouth. (Only one opening that is both the mout and anus.) The main waste product is ammonia.

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">**Nervous:** Cnidaria have no brains or central nervous system. They have nerve nets consisting of sensory neurons that generate signals in response to various types of stimulus.

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">**Reproduction:** Cnidaria participate in both sexual and asexual reproduction. Sexual reproduction involves a complex life cycle in which a larva becomes a polyp and grows and splits in a process known as strobilation. Asexual reproduction involves dividing down the middle (budding) or regenerating after being fragmented. <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">**Bibliography:** <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">[] <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">[] <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">[][] <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">[] <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">[]

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">**Picture Sources:** <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">[] <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">http://tolweb.org/tree/ToLimages/reproduction.gif [] []