Ph. Porifera and

Ph. CnidariaBiology Two

DOL 31-33

6/29/2016

I. Phylum Porifera (sponges; “pore bearer”)A. General characteristics

1. simplest animals2. asymmetric3. aquatic habitats

a. typically marine4. live alone or in colonies

a. often members of reef habitats

B. Anatomy1. 3 cell layers, but lack true tissues

a. outer = epidermis1) covered in ostia

a) pores for entry of H2O, O2 & nutrientsb. middle = gel layer w/ specialized cells

1) amebocytes (a.k.a. archaeocytes) = transport nutrients, complete digestion

2) spicules = provide shape & support

c. inner = choanocytes (a.k.a. collar cells)

1) have flagella that extend inward to help circulate water through sponge

2. Inside of body is hollowa. central cavity = spongocoelb. large opening = osculum

1) wastes, excess water exit through it 2) aids release of sperm for sexual repro

C. Physiology1. Feeding, digestion

a. filter feedersb. intracellular digestion

2. Respiration, excretion by diffusion3. Lack nervous system4. Adults are sessile

a. juveniles swim or drift freely

5. reproduce sexually & asexuallya. sexual uses internal fertilization

1) hermaphrodites – form both sperm & eggsa) release sperm, drawn in by ostia

b. asexual uses budding, gemmules 1) can also regenerate from broken pieces

D. Sponge classes1. Class Calcarea

a. calcium carbonate spiculesb. shallow tropical marine habitatsc. small & irregularly shapedd. ex: yellow calcareous sponge, white

cryptic sponge

2. Class Demospongiaea. 90% of all spongesb. silicon dioxide or spongin spicules c. ex: bath sponge, orange elephant ear

sponge

3. Class Hexactinellidaa. silica spicules arranged in latticesb. deep water habitats

1) abundant in Antarcticac. cup, vase or urn shape d. ex: Venus flower basket

II. Ph. Cnidaria (“stinging nettle”)

A. General characteristics1. 4 main types

a. corals, anemones, jellyfish, hydra2. aquatic habitats

a. most are marine (except hydra)b. often part of reef habitats

3. radial symmetry4. carnivores5. sessile as adults

a. except jellyfish

B. Anatomy1. 2 main body forms

a. Polyp1) cylindrical body w/ mouth &

tentacles upward2) sessile3) corals, anemone, hydra

b. Medusa1) body = upside-down bowl w/ mouth &

tentacles facing down2) motile3) jellyfish & some hydrozoans

2. Two specialized tissue layers a. outer = ectoderm

1) aids movementb. gel layer in between = mesogleac. inner = endoderm

3. Tentacles contain cnidoblastsa. stinging cells w/ nematocysts

1) poisonous - paralyzes2) for defense, feeding

4. Center of body = gastrovascular cavitya. 1 opening serves as mouth & anusb. receives food, allows wastes to exit

5. Lack respiratory & excretory systemsa. simple nerve net between tissue layers

1) lack brain

C. Physiology1. Feeding

a. sting prey w/ nematocysts1) tentacles push food to mouth

b. extracellular digestion begins in gastrovascular cavity

c. intracellular digestion completes it2. Circulation, respiration, excretion by

diffusiona. digestive wastes exit mouth opening

3. Some specialized sense cellsa. nerve net coordinates tentacle movementb. statocysts aid vertical movement, balancec. eyespots (ocelli) detect light

4. Reproduction alternates during life cyclea. asexual by budding or fissionb. sexual

1) corals - internal or external fert.2) anemones – both eggs & sperm leave

body & fertilize externally3) jellyfish – males spawn, females carry

fertilized eggs in brooding pouches in tentacles or stomach

D. Cnidarian classification1. Class Anthozoa (“flower animal”)

a. corals, anemonesb. sessilec. found in reef habitatsd. ex: brain coral, rose bulb anemone

2. Class Scyphozoa (“cup animal”)

a. true jellyfishb. motilec. ex: Moon jellies (Aurelia), Lion’s mane jelly

3. Class Cubozoa (“box animals”)

a. box jelliesb. motilec. highly toxicd. ex: Gulf sea wasps, Irukandji jellyfish

4. Class Hydrozoa (“sea serpent animal”)

a. sessile or motile1) may float rather than be attached

b. freshwater or marinec. many are coloniald. ex: Portuguese man o’ war, Hydra