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Phylum Porifera

The Sponges

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Sponges– Over 7,000 species, approximately 40 species that occur in

local waters– 2% of all sponges are freshwater, none are terrestrial

Phylum Porifera Overview

Most primitive of the multicellular animals– There is some debate if sponges are complex

colonial protozans and not metazoans.

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Phylum Porifera Overview

Sponges occur in shallow water habitats and vary widely in size (up to 1m. high) and shape

All sponges are sessile filter feeders

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Sponge Diversity

Yellow Tube Sponge

Black-ball sponge

Erect Rope Sponge

Porifera Anatomy

Thin, flat cells, called pinacocytes, line the outer surface of a sponge.

Some pinacocytes are specialized into tubelike, contractile porocytes, which regulate water circulation.

Below the pinacocyte layer is a jellylike layer called the mesohyl

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Porifera Anatomy

Mesenchyme cells move about in the mesohyl and can specialize to other functions including:– Reproduction– Secreting skeletal elements– Transporting and storing food– Forming contractile rings around openings in the

sponge wall

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Collar Cells

Choanocytes: (collar cells) act as a pump to bring water into the sponge

Create water currents for filter feeding

Choanocytes

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Sponge Support

Collagen is found between the inner canals and chambers– Mesohyl

Ameboid cells located in the mesohyl, have different roles– Archeocytes – Sclerocytes

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Sponge Support

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Spicules

Collagen is stiffened by adding microscopic mineral accretions or additional protein fibers (spongin) or both.– Spicules: skeleton

structures, made of calcium carbonate (CaCO3) or silicon dioxide (SiO2).

Spicules

Sponge Types- Ascon

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Sponge Types- Sycon

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Sponge Types- Leucon

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Porifera Reproduction

Asexual budding Regeneration: can regenerate from broken

pieces Gemmules- resistant capsules Sexual – Usually hermaphroditic (monoecious) with male and

female cells scattered throughout the connective tissue

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Porifera Larvae

Neighboring sponges are fertilized by sperm entering through the ostia– Ciliated mouth less

larvae (parenchymella) is released. Parenchymella

Sponge Life Cycle

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Porifera Classification

Phylum Porifera– Class Calcarea– Class Demospongiae– Class Hexactinellida– Sclerospongiae is no

longer considered a class

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Class Calcarea

Have spicules made of calcium carbonate

Mostly small in size (<15 cm.), and form irregular masses

Never contain spongin, restricted to shallow water, and strictly marine

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Class Demospongiae (Most sponges)

Have spicules made of silicon dioxide (SiO2) or spongin or a combination of both

Most sponges belong to this class (90%)

– Nearly all are leuconoid body type

Mostly found on the continental shelf

Spongia spp. (Bath sponge)

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Class Hexactinellida (Glass sponges)

Spicules are made of silica Usually found in deep water on soft substrates in the

tropics 200-1,000m. Spicules are six pointed and have a lattice-like structure Cup, vase or urn shape

Euplectella (Deep sea Glass sponge)