Porifera-The sponges

Porifera

Venus’s Flower Basket w/ Wedding Shrimp

Porifera I. Considered simple animals as they consist of many cell types with special functions & they lack tissues and organs. II. Their skeleton can be composed from two materials: 1. spongin (a soft, flexible organic material - made of the protein collagen) 2. spicules (small rods of calcium carbonate or silica) III. Fossil sponges are among the oldest known animal fossils

Porifera IV. The approximately 5,000 living sponge species are classified in the phylum Porifera which is composed of three distinct groups 1. Hexactinellida (glass sponges) 2. Demospongia 3. Calcarea (calcareous sponges)

Porifera V. Sponges are characterized by the possession of a feeding system unique among animals 1. No mouths 2. 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.

Porifera VII. Life style 1. Sponges are ubiquitous benthic creatures 2. Found at all latitudes beneath the world's oceans, and from the intertidal to the deep-sea 3. 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.

Porifera VIII. Sponge bodies 1. Diverse in form-determined by a. space to live b. type of material to attach to c. water currents 2. Encrusting sheets 3. Volcano-shaped mounds 4. Tubes as small as one millimeter or as large as one meter 5. 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.

flagellum collar osculum spicules mesenchyme pore cell nucleus water food vacuole pore cell H2O filled chamber nucleus water water collar cell amebocyte outer flat cells pore cell incurrent pore amebocyte cell

Porifera 7. 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)

Porifera b. 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.

Stop p1 P2 start of diagram P3 after diagram

Porifera Hexactinellida (glass sponges)

Class Hexactinellida (Hyalospongiae) 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

Greater than 90 percent of the 5,000 (?) known living sponge species. 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)

Class Calcarea (Calcispongidae) 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.