Phylum Cnidaria

General Characteristics About 9000 species _____________________ Simple nervous system __________________ Diploblastic organization Endoderm Ectoderm

General Characteristics Cont’d- Either tubular or bell shaped _______________________ Only animal with cnidocytes Cnidocytes-specialized stinging cells (on tentacle) All marine (aquatic)

____________________________ Cnidarians’ bodies are organized around the gastrovascular cavity, where digestion takes place GV has a single opening that serves as both mouth and anus

Gastrodermis: lines GV cavity 2 Layers of Cells Diploblastic: __________________________ Gastrodermis: lines GV cavity Epidermis: lines the outside of the body (the skin)

In between the two layers is the _________- a jelly-like substance.

Cnidarian Body Wall

Stinging Cells Have Cnidocytes ________________ Contain nematocysts: barbed thread-like structures inside the cnidocyte that shoots out and can puncture and poison or entangle prey

Cnidocyte

Feeding _______________________________ Inner gastrodermis secretes digestive juices into gastrovascular cavity which digests food and circulates nutrients

Feeding Cont.

Nervous and Movement _________________ & sensory receptors Muscles help in directional movement & capturing prey

_______ Medusa Life Cycles Cnidarians have two body forms that are representative of the sexual and asexual life cycles that they undergo. _______ Medusa

Polyp _______ Usually attaches to a substrate at the aboral end Oral end is surrounded by feeding tentacles

Medusa _________ ________________ Sexual (dioecious) Shaped like an upside-down bowl Tentacles surround the mouth that is housed underneath the bell

When cnidarians display both forms at some point in their lives, they are said to display an __________________________

_________________________ Both sexual and asexual Sexual Gametes released into water Fertilization takes place to create free-swimming planula Asexual By budding

Generalized Cnidarian Life Cycle

__________________________ Scyphozoa: Jellyfish Anthozoa: Sea anemones & Corals Hydrozoa: Hydra Cubozoa: Box Jellies

Class Hydrozoa Ex. Hydras

__________________ Includes hydras, fire corals, and Portuguese Man of War Display alternation of generations Polyp Medusa

Class Scyphozoa True Jellyfish ___________________________ Small polyp stage during life cycle

_____________________ Similar to Scyphozoans, except that their medusa is cuboidal Includes the box jellyfish 1 of the 10 most venomous animals on the planet Kills 12 people per year

Class Anthozoa Polyps that are flower-like ___________________ Includes sea anemones, corals, sea whips, and sea fans