SpongesChapter 9 Section3

Sponges

Live all over the world (oceans, freshwater rivers and lakes)

Sponge: Body Structure

Invertebrate animalsNo body symmetryNever have tissues or organsLooks like a hollow bag

◦Large opening at one end and tiny pores covering the surface

Spikes support and protect sponges body

Sponge: Obtaining Food and Oxygen

Eats tiny single-celled organisms

Collar cells that line central cavity, trap the tiny organisms

Jelly-like cells inside sponge digest, or break down, the food

Sponges get oxygen from water

Sponges: Reproduction

Asexually◦Budding: small new structures grow from the

sides on an adult sponge◦Buds eventually break free and begin new life

Sexually◦Sponges produce both sperm cells and egg

cells (do not have separate sexes)◦Sperm cells released in water, enter another

sponge, fertilize its eggs, larva develops◦Larva: immature form of an animal that looks

very different from the adult

CnidariansChapter 9 Section3

Cnidarians

Jellyfish, corals, and sea anemonesInvertebrates that have stinging cells

to capture food and protect themselvesTake food into central body cavity

Cnidarians: Body Structure

Two different body plans (vase and bowl)

Radial symmetryCentral hollow cavityTentacles containing stinging cells

Body Structure:Polyp

Vase-shaped body plan is a POLYPSea anemoneMouth opens at topTentacles spread out from around mouth

Most are attached to underwater surface

Body Structure:Medusa

Bowl-shaped body plan is a MEDUSA

JellyfishAdapted for a swimming lifeMouths open downward and

tentacles trail down

Obtaining Food

Use stinging cells to catch animals they eat (prey)

Contains threadlike structure with spines

Uses tentacles to pull prey to mouthTakes food into central body cavity Expels undigested food through mouth

Movement

Unlike adult sponges, many cnidarians move to escape danger and to obtain food

Jellyfish?

Sea Anemones?

Reproduction

Asexual Reproduction◦Hydras, corals, and sea anemones

Sexual Reproduction◦Jellyfish

Life in a Colony

Colony◦a group of many individual animalsStony corals and Portuguese man-of-war

Stony Coral

a coral reef is built by cnidarianscoral reefs are home to more species

of fishes and invertebrates than any other environment on Earth

Coral polyps produce hard, stony skeletons around their soft bodies

Portuguese Man-of-War

Contains as many as 1,000 individuals that function together as one unit

Top: gas filled chamber, allows colony to float

Bottom: polyps with different functions drift below◦Some catch prey and help with digestion and reproduction