1 / 11

Cnidarians

Cnidarians. Ms. Moore 2 /5/13. What is a Cnidarian?. The phylum Cnidaria includes: hydras, jellyfish, sea anemones, and coral. Cnidarian = soft bodied, carnivorous animals that have stinging cells arranged in a circle around their mouth.

shilah
Download Presentation

Cnidarians

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cnidarians Ms. Moore 2/5/13

  2. What is a Cnidarian? • The phylum Cnidaria includes: hydras, jellyfish, sea anemones, and coral. • Cnidarian = soft bodied, carnivorous animals that have stinging cells arranged in a circle around their mouth. • They are the simplest animals to have body symmetry and specialized cells. • Cnidocytes: stinging cells located along their tentacles • Nematocyst: poison-filled, stinging structure with dart

  3. Form and Function • Body Plan = radially symmetrical, central mouth surrounded by many tentacles • 2 Stage Life Cycle • Polyp: cylindrical body with arm-like tentacles; sessile; mouth pointing upward • Medusa: motile body with mouth pointing downward • Both stages have internal space called gastrovascular cavity, this is where digestion occurs

  4. Feeding = after paralyzing their prey, Cnidaria pulls it into its gastrovascular cavity • Digestion starts outside cells in the gastrovascular cavity and finishes inside. Anything indigestible is pass out the mouth. • Respiration, Circulation, and Excretion • Cnidarians respire and eliminate wasted by diffusion through body walls • Response = nerve net that is spread throughout their body and allows detection of stimuli • Statocysts: detect direction of gravity • Ocelli: detect light with eyespots

  5. Movement = various • Hydrostatic skeleton: layer of circular muscles and a layer of longitudinal muscles that use water of GV cavity to move • EX: jellyfish move by jet propulsion • Reproduction = sexual & asexual • Polyp: budding (asexual) to make identical offspring or tiny medusas that grow into adult • External fertilization: sperm and egg unite in water outside body; zygote grows into larva; attach to surface and develop into embryo

  6. Groups of Cnidarians • Jellyfishes: can be 4m in diameter and the tentacles can get up to 30m long; reproduce sexually • Class: Scyphozoa, “cup animals” • Hydras & relatives: most common body form is polyp; get energy from stinging and digesting small prey or symbiotic relationships; produce sexually or asexually • Class: Hydrozoa • Sea Anemones & Corals: have only polyp stage; reef can be several various forms; central body with many tentacles; Anemones live at all depths; use nematocyst to catch prey; repreduce sexually or asexually; grow colonial (with others) and secrete calcium carbonate (limestone) • Class: Anthozoa, “flower animals”

  7. Ecology • Cnidarians distrubution around the world depend on temperature, water depth, and light intensity • Light is used in the symbiotic relationships by photosynthetic organisms = 60% energy • Damaging to corals: logging, farming, bleaching, fertilizer

More Related