Porifera-The sponges

Porifera

PoriferaI. Considered simple animals as they consist of many I. Considered simple animals as they consist of many

cell types with special cell types with special functionsfunctions & they lack & they lack tissues tissues and and organsorgans. .

II. Their skeleton can be composed from II. Their skeleton can be composed from twotwo materials: materials: 1. 1. sponginspongin (a soft, flexible organic material - (a soft, flexible organic material - made of the proteinmade of the protein collagen collagen) ) 2. 2. spiculesspicules (small rods of (small rods of calciumcalcium carbonate carbonate or or silicasilica))

III. Fossil sponges are among the oldest known III. Fossil sponges are among the oldest known animal fossilsanimal fossils

PoriferaIV. The approximately IV. The approximately 5,0005,000 living sponge living sponge

species are classified in the phylum Porifera species are classified in the phylum Porifera which is composed of which is composed of threethree distinct groups distinct groups

1. Hexactinellida (1. Hexactinellida (glass glass sponges)sponges)2. 2. DemospongiaDemospongia3. Calcarea (3. Calcarea (calcareouscalcareous sponges) sponges)

PoriferaV. Sponges are characterized by the possession of a feeding system unique among animals

1. No mouths2. Pores in their outer walls through which water is drawn 3. Cells in the sponge walls filter items from the water 4. H2O flow is unidirectional, driven by beating flagella which line the surface of chambers connected by a series of canals. 5.Sponge cells perform a variety of bodily functions and appear to be more independent of each other than are the cells of other animals

VI. They are predominantly marine.

PoriferaVII. Life style

1. Sponges are ubiquitous benthic creatures2. Found at all latitudes beneath the world's oceans, and from the intertidal to the deep-sea3. Generally, they are sessile*, some are able to move slowly (up to 4 mm per day) within aquaria. 4. Some sponges bore into the shells of bivalves, gastropods, and the colonial skeletons of corals by slowly etching away chips of calcareous material.

*Another interesting thing can happen when a sponge settles on a snail shell that is being used by a hermit crab. This sponge/crab association results in a sponge that gets around.

PoriferaVIII. Sponge bodies

1. Diverse in form-determined by a. space to liveb. type of material to attach to c. water currents

2. Encrusting sheets3. Volcano-shaped mounds4. Tubes as small as one millimeter or as large as one meter5. Upright sheets like elephant ears.

Porifera

6. In all cases, poriferans have a canal system, through which they pump water. Water enters through pores called ostia, flows through canals to a spacious chamber called a spongocoel, and finally exits through large openings called oscula.

Porifera7. Often, sponges are distinguished by the

level of complexity exhibited by their bodies.

a. The simplest form consists of a single tube two cell layers thick. Poriferans with this type of architecture are necessarily very small due to surface area to volume constraints (Ascon)

Poriferab. For a sponge to attain greater size, the sponge wall must be folded in on itself.

i. A simple folding of the wall yields a sponge body with

sycon organization. ii. The vast majority of sponges

are organized in a more complex way, the leucon condition, with folds upon folds, resulting in a series of flagellated chambers connected by canals.

iii. Ascon, sycon, and leucon are levels of complexity that

grade one into the other.

PoriferaHexactinellida (glass sponges)

Taxonomy cont.

Class Hexactinellida (Hyalospongiae)(Glass Sponges)

• Characterized by siliceous spicules • Lack an outer layer• Usually cylindrical, or funnel- shaped• Most live in deep waters.• Widely viewed as an early branch within the Porifera

Porifera Demospongiae - 90% of all sponges

Taxonomy cont.

Class Demospongiae(Demosponges)

• Greater than 90 percent of the 5,000 (?) known living sponge species.• Most colorful• Demosponge skeletons are composed of spongin fibers and/or siliceous spicules• All members express the leuconoid body form• Can be found in fresh water

Yellow sponge growing on a wall on a Caribbean reef.

Porifera Calcarea (calcareous sponges)

Sponge Taxonomy

Class Calcarea (Calcispongidae)

(Calcareous Sponges)• Only sponges that possess spicules composed of calcium carbonate.• Typically pale in color• Tendency to be quite small in size (less than 30cm)• This class of sponges lacks spongin• They are quite brittle to touch• They are usually found in shallow water.