phylum cnidaria
DESCRIPTION
ANIMAL TAXONOMYTRANSCRIPT
PHYLUM CNIDARIA
Presented by:
Gabitan, John PauloTero, Nariza L.Valencia, Juliet D.Zapanta, Schola Marie
• Radially symmetrical cnidarian body is organized as a hollow sac with the mouth and surrounding tentacles located at one end.
• Based on molecular data, some systematists have proposed that cnidarians share a common ancestor with the clade of bilateral animals.
• Cnidarians have two body shapes: polyp and medusa.
• Polyp form, represented by hydra, typically has dorsal mouth surrounded by tentacles.
• Medusa form, the mouth is located in the lower concave or oral surface; the convex upper surface is the aboral surface.
• Cnidarians get their name from specialized cells called cnidocytes that contain stinging organelles.
• It is found mainly in epidermis especially on tentacles.
• Cnidocytes contain stinging “thread capsule” called nematocysts
• Cnidarians use their tentacles to capture prey and they push it into the mouth and it leads to gastrovascular cavity, where digestion takes place.
• Mouth is the only opening into gastrovascular cavity that serves for both ingestion of food and expulsion of undigested material. Gas exhange and excretion occur by diffusion.
• Cnidarians are diploblastic meaning thay have 2 definite tissue layers.
• Ectoderm which give rise to outer (covering of body) and endoderm gives rise to inner gastrodermis, which lines the gastrovascular cavity and functions in digestion.
• These thin layers are separated by a thick, jellylike mesoglea, which is mainly acellular.
• Cnidarians have nerve cells that form nerve nets connecting sensory cells in the body wall to contractile cells and gland cells.
• Hydrostatic skeleton supports the body and allows movement.
GROUPS
HYDROZOANS
SCYPHOZOANS
CUBOZOANS
ANTHOZOANS
HYDROZOANS
HYDRA
• Mainly marine but some are freshwater species
• Alternation of polyp and medusa stages in most species (polyp form only in Hydra)
• Some form colonies
SCYPHOZOANS
• “True” jellyfish• Mainly marine• Typically inhabit
coastal water, free swimming medusa most prominent form• Polyp stage is often
reduced
JELLYFISH
CUBOZOA
BOX JELLYFISH
• Inhabit tropical and subtropical waters
• Have polyp stage but medusa form most prominent
• Square shape when viewed from above
• Actively hunt prey• Complex eyes that
form blurred images
ANTHOZOA
SEA ANEMONES
• Marine• Solitary or colonial
polyps• No medusa stage
in most• Gatrovascular
cavity divided by partitions into chamber, increasing area for digestion
REPRESENTATION ORGANIZATION
ECONOMIC IMPORTANCE
• Coral reefs (Anthozoans) serves as a habitat of fishes and this may also serve as a tourist attraction to humans.
• They also provide a home for algae which creates oxygen that we breathe. The coral reefs are also important because the polyps, algae, and animals in that habitat are a major food source for other animals.