SPONGES PORIFERA

I was part of the Cambrian explosion!

Where do they live? In fresh and salt water

Extremely porous; names means “pore- bearer” No gastrula stage; loose multicellular organization; no true tissues Sessile as adults - attached

Body Plan Asymmetrical; hollow cylinders with top opening “osculum”, lined with collar cells with flagella “choanocytes” to circulate water, nutrients, wastes, and gases for respiration. Water enters through the pores and exits through the osculum.

OSCULUM

Chonaocytes could be derived from the ancestors of the animal kingdom, the chonanoflagellates.

skeleton made of: –(a) spongin – made of the protein collagen –(b) spicules – made of calcium carbonate or glasslike silica spongin spicules

How they feed Filter-feeders contain amoebocytes – specialized cells that move nutrients, wastes, and sperm and also make spicules

osculum choanocyte flagellum spongocoel amoebocyte pore spicule pinacocyte mesenchyme (Jelly-like material)

No nervous system but some secrete toxins

Reproduction Asexual – form buds (gemmules) during hard times; also regeneration (replacing lost body parts) Sexual – flagellated sperm swim into pores and fertilize the egg. The larva is flagellated and can swim away.

Sponges are hermaphroditic and can produce both eggs and sperm. They do not self-fertilize. Eggs and sperm are produced at different times.

Sponge Development

Importances of the Sponges Habitats for many aquatic organisms

Symbiotic relationships with photosynthetic organisms; sponge provides protection for food from the partner; may help in camouflage - ex. sponge crab

Commercial use

Can you find the sponge crab?

CNIDARIA Jellyfish, corals, sea anemones and other stingers...

Characteristics Soft-bodied, carnivorous animals with stinging tentacles Name Cnidaria comes from their cnidocytes, or stinging cells. The cnidocytes contain nematocysts which is the stinging structure.

Cnidarians are Protostomes which means their mouths develop first from the blastopore opening.

Body Structure: Have true tissues and TWO cell layers: - an epidermis derived from ectoderm - a gastrodermis derived from endoderm which lines the gastrovascular cavity A jelly-like substance, mesoglea, is found between these layers and may be very prominent as in the jellyfish.

mesoglea

Cnidarians have two cell layers.

have radial symmetry have two body shapes: polyp - vase-shaped and medusa – bell-shaped Some exist as colonies of both shapes such as the Portuguese Man – of – War. Polyp forms are sessile or attached. Some can move infrequently though.

Is this a polyp or medusa?

Have only ONE opening, hence a “sac” gut. Digestion takes place extracellulary in the gastrovascular cavity and food particles diffuse into the cells. Flagellated cells move water through the cavity. They depend on diffusion to move nutrients, waste, and gases through their bodies.

Basal disk Mouth/anus EPIDERMIS

new features… The first animals to have a diffuse nervous system (nerve net) Also have specialized cells to determine a sense of gravity Have eyespots to sense light

We can move… For movement, the first animals to have muscles. Their skeleton is hydrostatic (water supported with muscles) Some jellyfish use jet propulsion for movement.

How do we reproduce? Reproduction can be asexual by budding in warm weather or sexual, involving EXTERNAL fertilization. Sexes are separate. The larva is free-swimming. Some members go through both body types and sexual and asexual reproduction in their life cycles, such as the Aurelia jellyfish.

Asexual reproduction in the hydra Bud

Aurelia – showing both asexual and sexual reproduction Tutorial 32.1 Life Cycle of a Cnidarian

Aurelia jellyfish Ciliated larvae

Importances of the Cnidarians Many depend on symbiotic relationships with algae for food (also give them color). Zooxanthellae

Symbiotic relationships with other animals

Corals are small polyps that live in colonies and secrete an underlying skeleton made of calcium carbonate (limestone) which form coral reefs.

The little coral animals look like tiny sea anemones poking out of their limestone skeleton

The coral pieces you see on the beach are skeletons that are left over after the coral animals have died.

How are coral communities threatened? Coral communities are threatened by Overfishing Sediments from logging clouding the water preventing photosynthesis of the symbiotic algae Human damage from walking on them or dropping boat anchors on them High temperatures causing bleaching or death of the coral animals and/or the algae.

Coral reef distribution Variables that affect coral reef distribution: temperature, water depth, light intensity.

Coral Bleaching

If the present rate of destruction continues, 70% of the world's coral reefs will be destroyed by the year 2050.

Take care of our coral!

Sea Fans Sea fans are corals with an internal limestone skeleton.

Classes of Cnidarians Scyphozoa – jellyfish; medusas only

The Box Jellyfish is said to be the most toxic of all jellyfish and a sting from them can easily kill a human because their venom leads to paralysis, which often leads to drowning. The majority of jellyfish stings occur in the Atlantic Ocean (near Florida) and along the eastern coast of Australia. Death Toll: 100+ per year

Hydrozoa – hydras, Portuguese-Man-of-War; Hydras are polyps; P. Man of War is a colony of polyps and medusas.

Hydras are good cnidarians to look at in our class.

Basal disk Mouth/anus EPIDERMIS

Anthozoa – sea anemones, corals, sea fans; polyps only

Now, that is a jellyfish!