SPONGESSPONGES

PHYLUM PORIFERAPHYLUM PORIFERA

Major Characteristics of the Phylum Porifera

•Sponges are:• asymmetrical • multicellular• sessile• Heterotrophic• eukaryotic• No body cavity• evolved from Kingdom Protista• No systems (digestive, excretory, circulatory, or respiratory)

Water flowing through sponges provides food and oxygen, as well as a means for waste removal.

Green dye was placed next to a sponge-- note the flow from the osculum!

Small incurrent pores allow water in.

SpongesSponges

Cell types (3 types)

1. Choanocyte cells (a.k.a. “collar cells”) have “nets” and flagella. They surround pores, bring water in, and filter food particles.

2. Epithelial cells—often brightly colored.

Cell types (2nd type)

Amoebocyte cells have many jobs:•transport food•replace damaged parts•produce spongin spicules•form gametes

Cell types (3rd type)

amoebocyte

BARREL SPONGES

ReproductionMost are hermaphrodites-- produce both male and female gametes.

Sexual Reproduction

Amoebocytes become:

•Eggs--retained and fertilized internally

•Sperm-- released through osculum

{sperm osculum other sponge’s choanocytes amoebocyte carries sperm to egg) fertilization forms larva (plankton) released from mesenchyme, then floats/swims to new spot develops to adult}

Asexual reproduction is also possible:

gemmules (freshwater sponges only)fragmentation (following damage)

OLD PICTURE FROM FLORIDA OF SPONGE COLLECTORS

STINGING CELLEDSTINGING CELLED

PHYLUM CNIDARIANPHYLUM CNIDARIAN

Characteristics of Cnidarians

• Evolved by gaining body symmetry and Evolved by gaining body symmetry and tissuestissues

• Radially-symmetrical Radially-symmetrical

• no body cavityno body cavity

• Digestive cavity and mouth for digestion, Digestive cavity and mouth for digestion, excretion, circulation, and respirationexcretion, circulation, and respiration

Cnidarian CharacteristicsCnidocytes -- stinging cells-- barbed &/or sticky &/or poisonous-- used for feeding / protection

Gastrovascular cavity-- food and oxygen in / waste and CO2 out

Tissues-- muscular, nervous (sensory and nerve-net cells), mesoglea (from ectoderm and endoderm)

Hollow body form(s)-- sessile, vase-shaped polyp &/or free-swimming, bowl-shaped medusa

Planula-- free-swimming larval form resulting from sexual reproduction (sexual and asexual reproduction)

Three Classes of Cnidarians

1. Hydrozoans-- (Hydra, Portuguese man-of-war, Obelia)

Polyp formMostly asexual reproductionFreshwater and marine types

2. Scyphozoans-- jellyfish (stinging nettle, blue wasps...)

Medusa form dominant1/2 inch to 7 feet diameterNerve cells in margin of bell (coordinate swimming)Sense organs-- statocysts (gravity) and ocelli (light)Some are edible (juicy mesoglea!)

Video

3. Anthozoans-- anemones and corals (red coral, sea fans…)

Polyp form only (thus sessile except for planula and those living on backs of snails)Anemones lack skeleton; corals secrete CaCO3 (limestone)

Many have symbiotic dinoflagellates &/or green algaeSexual and asexual reproductionDivided, sophisticated gastrovascular cavityForm coral reefs of limestone skeletons-- most diverse marine communities-- provide food and shelter for fish, shellfish, etc.Red coral used for money/jewelry