Phylum Cnidaria & Ctenophora Kingdom: Animalia Phylum Cnidaria Class Hydrozoa Class Scyphozoa Class Anthozoa Phylum Ctenophora

Major Characteristics Presence of specialized tissues Also called Coelenterates Comprised of sea anemones, jellyfish, corals Have radial symmetry Two forms polyps and medusa

Body Structure All have radial symmetry, where similar parts of the body are arranged and repeated around a central axis

Radial vs. Bilateral Symmetry Diagram A

Radial Symmetry

Two Main Body Forms - Polyp A polyp is a sac like stage. Sessile or non-motile

Two Main Body Forms - Medusa A medusa is bell-like, which is similar to an upside down swimming polyp Free floating or swimming

Polyp vs. Medusa Some spend their life as both at some point or as one or the other the entire time Diagram B

Polyp vs. Medusa Diagram D

Three Basic Layers:

Three Basic Layers Ectoderm/Epidermis – outer layer that contains the stinging cells Endoderm/Gastrodermis – lines the gut Mesoglea – Jelly like substance in between the Ectoderm and Endoderm which contains scattered cells and collagen fibers

Exoskeleton Coral will create a calcium carbonate shell in which it will live

Body Structure The mouth is located on the top of the polyp or underside of the medusa It is the only opening on the organism so is also shares the function of being an anus Diagram E

Body Structure Diagram F

Tentacles Slender finger like structure used to capture and handle food Location of nematocysts

Nematocysts The main characteristic of Cnidaria is the presence of nematocysts Stinging structures found on the tentacles

Nematocysts Coiled – like stinger Spring into the prey and releases toxin Most not harmful to humans because they cannot penetrate skin Some fatal

Nervous System Main characteristic is the presence of a nerve net Nerves cross over each other, at every connection, communication occurs In humans millions cross over millions and no communication occurs

Nerve Net Diagram C

Digestive System All cnidarians are carnivorous Paralyzed by the nematocysts Enzymes in gastric cavity break down the food and nutrients are absorbed by cells in the endoderm Wastes are sent out the mouth/anus

Digestive System

Reproductive Cnidarians have the ability to reproduce sexually and asexually One method that is commonly seen is budding

Class Anthozoa Largest group of Cnidarians Stay in the polyp stage throughout life cycle Solitary or colonial Includes sea anemones

Class Hydrozoa Can consist of just a polyp stage, just a medusa stage, or both Can join together to form complex colonies such as the Portuguese Man-O-War, which develop floats FLOAT

Class Scyphozoans BELL Medusa is the dominant life stage Swim with rhythmic contractions of the bell, though limited Contain the most dangerous/fatal stings BELL

Phylum Ctenophora Comb Jellies Not a member of the Cnidarian Phylum even though they share similarities

Cnidaria vs. Ctenophora Have cilia at the base of the medusa to move Engulf food Do not have nematocysts Have an additional layer between endo and ecto layers Anal pore