Chapter 12 - Phylum Porifera

Budding

Many sponges reproduce by budding, a process in which the sponge begins as a small growth that appears at the base of the parent sponge. The new sponge grows larger and eventually either separates from the parent or increases the size of the group.

Syconoid

In this type of canal system, incurrent canals (opening from the outside) lie alongside radial canals, opening into the spongocoel.

Leuconoid

In this type of canal system, the canals form a complex, branching, network.

Asconoid

In this type of canal system, the canals pass directly from the ostia to the spongocoel, which is lined with collar cells.

The body wall is made up of...

1) An outer epidermis (dermal epithelium) of thin, flat, cells. 2) A gelatinous mesenchyme that contains amoebocytes and spicules. 3) An inner lining of flagellated collar cells, or choanocytes.

Classes of Sponged

1) Calcarea (with calcareous spicules). Canal systems of asconoid, syconoid, or leuconoid design. 2) Hexactinellida (six-rayed siliceous spicules). Glass sponges. Syconoid and leuconoid canal systems. 3) Demopongiae (with a skeleton of siliceous spicules and/or spongin). Leuconoid canal system.

Skeletons may consist of...

1) Spicules of calcium carbonate (calcareous spicules). These are spicules that are composed of calcium carbonate (CaCO3) Example: Grantia 2) Spicules of siliceous material. These are composed of silicon dioxide (SiO2). Example: Glass sponges 3) Spongin, a proteinlike substance. The skeletal framework consists of a network of protein fibers. Examples: Bath sponges, fresh water sponges.

Gemmules

Asexual reproduction by buds or gemmules and sexual reproduction by eggs and sperm; free-swimming ciliated larvae. Gemmules are formed in response to the onset of harsh conditions. Gemmules form as archaeocytes come together in the mesohyl and rapidly divide by mitosis.

Sessile

Attached to the bottom and cannot pursue their food. Therefore, sponged depend upon the water drawn in through these tiny pores and canals for obtaining food and oxygen and eliminating waste.

Totipotent

Most of the body cells are totipotent, retaining the ability to differentiate into other types of specialized cells.

Viviparous

Most species of sponges are viviparous - the zygote is retained within the parent's body until a ciliated larva is produced. The larva may swim for about several hours or several days before settling to the bottom and attaching to develop into a new sponge.

Hermaphroditic

Most sponges are monoecious or hermaphroditic, that is, both male and female sex cells are found in one individual; some are dioecious. Hermaphroditic individuals may change their sex so that eggs and sperm are produced at different times.

The sequence of water flow is...

Ostium -> incurrent canal -> prosopyle -> radial canal -> apopyle -> spongocoel -> osculum

Prosopyles

The incurrent canal is connected to another canal lying next to it known as the radial canal by small openings known as prosopyles.

Choanocytes

The canals and chambers within the sponge are lined by flagellated collar cells.

Spongocoel

The cavity within the sponge. The central cavity of the sponge is known as this.

Osita

The name Porifera means "pore bearing" and refers to the many tiny pores or ostia that open to the surface of the sponge.

Spicules

The skeleton of sponged consists of calcareous or siliceous spicules or of protein spongin.

Osculum

The spongocoel has a large opening at the top called this.

Filter Feeding

The type of feeding employed by sponges is known as this. A process in which minute food particles are extracted from the water as it passes through tiny canals and chambers that act as strainers.

Apopyle

The water in the incurrent canal passes into the prosopyle and then passes into the radial canal. From here, water passes through an opening called apopyle, enters the spongocoel and then exits the sponge through the osculum.