CH 13: Cnidarians and Ctenophorans

All cnidarians possess ______ , which have ________ responsible for stinging.

cnidocytes, cnidae

____ are a unique cell type to the phylum and are called a ____ during development

cnidocytes, cnidoblast

Nematocysts trigger ______ , a modified cilium

cnidocil

Cnidarians have the longest fossil history of ____

700 my

______ are specialized organelles that require slight stimulation to fire a chemical projectile containing a toxin.

Nematocysts

one individual benefits, one experiences no effect

commensalism

one individual benefits, the other experiences a loss

parasitism

both individuals benefit

mutualism

Cnidaria characteristics

Radially or bi-radially symmetrical

Have polyps and medusae

Diploblastic with mesoglea

Extracellular digestion

Simple nerve net

No excretory or respiratory system

No coelomic cavity

Medusae

Tetramerous (4 body part symmetry)

Statocysts for orientation and ocelli for light reception

The body wall of cnidarians consists of outer _____, inner _____, and ____ between.

endodermis, gastrodermis, mesoglea

Cnidarians contain no true _____ cells

muscle

Polyps reproduce asexually via _____ , ______ , ______

budding, fission, pedal laceration

______ occurs when water gets too warm, leading to the eviction of algae from coral polyps.

coral bleaching

Cnidarians have no centralization, but have ________ which are sensory cells that are a precursor to centralization

rhopalia

In Class Hydrozoa, the developmental layer from ____ called __ differentiates into muscles.

ectoderm, entocodon

Mouthlike structure located on top of a cone-like structure in Hydra sp.

hypostome

This picture is of a Hydra sp. eating a what?

water flea

Class Scyphozoa contains most of the

jellyfish

Aurelia life cycle: Strobilation:

the process by which Aurelia makes saucer like buds called ephyrae and becomes a strobila (chain).

Octocorallian Corals: Order Alyconaria

octomerous symmetry (Eight pinnate tentacles)

Coral reefs are made from _____ corals and ____ algae

hermatypic, coralline

Zooxanthellae

photosynthetic algae living within coral tissues, functioning as primary energy producers in a symbiotic relationship

Corals and sea anemones primarily engage in __ mutualism with photosynthetic dinoflagellates.

endosymbiotic

_______ reefs are parallel to shore and has a wider and deeper lagoon than a fringing reef

barrier reef

_____ reefs, which circle lagoons but not islands.

atolls

Cnidarians have a simple __ which allows for two-way transmission without myelin.

nerve net

Phylum Ctenophora is characterized by __, which means they bear combs.

Kteis or kronos

Phylum Ctenophora are

carnivorous