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Home , Cnidocyte, Jellyfish, Sea anemone

Fungi ANIMALIA Choanoflagellates Porifera () ANIMALIA

Multicellularity (comb jellies)

Cnidaria (, , ) Diploblasty Acoela (acoels)

LOPHOTROCHOZOA Rotifera () Loss of Platyhelminthes Triploblasty () Segmentation Annelida

(segmented worms)

Protostome development (, clams,

squid)

ECDYSOZOA Nematoda (roundworms)

Cephalization, CNS, coelom Arthropoda Segmentation (insects, , )

DEUTEROSTOMES Radial symmetry Echinodermata (in adults) (sea stars, dollars) development Chordata Segmentation (, )

A ctenophore, or comb jelly

Phylum Ctenophora Ctenophore Cnidarians: Hydrozoans (top left), jelly (top right), sea (bottom left), polyps (bottom right) General Cnidarian characteristics

• Radially Symmetric • Diploblastic (, gastrodermis) • No cephalization, No central • No special respiratory, excretory or circulatory organs • Primarily Carnivores • and Medusa body forms Polyp and medusa forms of cnidarians

pelagic sessile

Have no separate gut, (just GV cavity/body wall) and only one body opening. This has several consequences:

• Food and undigested waste pass through same opening in different directions

• Movements of body cause distortion of GV cavity

• GV cavity serves for both circulation and digestion

• Gametes and embryos must be released through the same opening The Hydrostatic

• Uses fluid (water) in a body compartment for support and transmission of muscular forces

• Fluid is incompressible, force generated by displacement of fluid in one region, can be used to do work in another Figure 5.2

11 Figure 5.3

12

Figure 6.23

14 • Epithelio-muscular cells (longitudinal)

• Nutritive-muscle cells (circular)

15 Many Cnidarians have endosymbiotic () within their cells – very important !

Sea anemone Coral polyps with endosymbiotic zooxanthellae () Endosymbiotic dinoflagellates (zooxanthellae) inside jellyfish cells with endosymbiotic green algae Almost all Cnidarians have cells called – which have called nematocysts. A of a hydra 22 Some Nematocyst types Hydra capturing Daphnid

Ingestion and Digestion Cnidarian Nerve Nets • Mostly non-polar synapses, so impulses can travel in either direction

• Signal diminishes with distance

26 Nerve cells in epithelial tissue of 28

Subphylum Class Class Cubozoa Class (used to be Class) Subclass Subclass Class Scyphozoa Jelly medusa Purple striped jelly, Pelagia panopyra

• Gastric filaments on the gonads secrete enzymes and then phagocytize partially digested food.

• Digestion occurs intracellularly within food vacuoles. Scyphozoan Rhompalia Figure 6.9

Senses light

Balance

35 Class Scyphozoa

Most Scyphozoans are Dioecious

Strobila life cycle Class Cubozoa

• Highly Toxic Nematocysts Class Hydrozoa Hydromedusae

velum

Scyphozoan medusae Hydra: an atypical Hydrozoan

Thecate hydroid

Athecate hydroid

Class Hydrozoa

Obelia

ephyra Colonial Hydroid Figure 33.7 The life cycle of the hydrozoan (Layer 1) Figure 33.7 The life cycle of the hydrozoan Obelia (Layer 2) Figure 33.7 The life cycle of the hydrozoan Obelia (Layer 3) Physalia, Portugese man-of-war

Order Siphonophora

Subphylum (class) Anthozoa

Coral polyps

Sea anemones Anthozoan polyps are larger and more complex than Hydrozoan polyps

No Medusa stage • Pharynx with siphonoglyphs

• GV cavity has mesenteries

Cross section A variety of Anthozoans Subclass Octocorallia

• Have 8 pinnate

• Some are called Gorgonians (sea fans, sea whips) Subclass Octocorallia

Sea Fan, a gorgonian

Sea Pens, a soft coral Coral Polyps are often retracted in the daylight

Renilla, the Subclass Hexacorallia

• Many tentacles, in multiples of 6

• Scleractinian corals may build reefs Secrete CaCO3 at the base Subclass Hexacorallia

Anemone – Papua New Guinea