Hydra, Jellyfish, Coral, & Sea Anemones
Phylum Cnidaria-
Examples
Sea Anemones and Corals - Anthozoa
Hydra- Hydrozoa
Jellyfish - Scyphozoa
Ctenophores - non stinging Cnidarians;
Comb Jelly
Anatomy
A. Polymorphism- Cnidarians have more than one body form:
1.Polyp
2. Medusa
Polyp Form
Tube with tentacles around the mouth
Sessile
Medusa Form
Umbrella Shape
Tentacles around mouth
Motile, Free-swimming
Tentacles
Have nematocysts (stinging cells) coiled thread discharges like a harpoon
Contains neurotoxin
Paralyzes prey
Level of Organization
A. Cnidarians have tissues
B. No Organs
C. Most Cnidarians have Radial Symmetry
Radial Symmetry
Radial
Habitat:
Aquatic:
1.Most Marine
2.Few Freshwater
Feeding
A.Carnivores (predators)
B. Process of feeding
1. Tentacles sting prey with
Nematocysts
2. Tentacles grab prey
3. Prey pulled into mouth
Process of feeding
4. Prey stuffed into gastro-vascular catvity (GVC)
5. GVC makes enzymes, extra cellular digestion
6. Undigested food back out mouth
Respiration
Via diffusion
Body is two cell layers thick
Internal Transport
Via diffusion
Response
A. No nervous system
B. Nerve net around mouth
Locomotion
A. Medusa- motile, free-swimming
B. Polyps- sessile, attached to hard substrate
Exceptions:
1. Hydra humbles on tentacles
2. Sea anemones glide on pedal disc
Reproduction
1. Asexual
Budding
2. Sexual
a. Medusae release sperm and eggs
b. Larvae are free-swimming
Ecological Role
A. Predators and prey
B. Neurotoxins in medical research
C. Coral - Jewelry , building, reefs (surfing)
D. Cora Reefs - habitat for many Great Biodiversity Protect coastline
E. Symbiosis with other organisms
Portuguese Man O' War ( a Hydrozoan) NOT a true jelly fish
Man O' War Can measure up to 30cms across
Crescent wind thing that glides it
Polyps can be either food gathers and some are reproductive.
As low as 10m long

Jellyfish