Phylum porifera
Poriferans are commonly referred to as sponges. There are approximately 5,000 sponge species that are classified in this phylum with majority of them marine and 150 of them living in fresh waters. They are sedentary, filter-feeding, metazoans which have a single layer of flagellated cells that drive a unidirectional current of water through its body.
ECOLOGICAL ROLE
Sponges provide a home for a number of small marine plants and animals which live in and around their pore systems. Sponges also provide support and protection for bacteria and algae and in return they provide the sponge with food. Sponges commercial use including bathing, padding and artistic uses.
Sponges provide a home for a number of small marine plants and animals which live in and around their pore systems. Sponges also provide support and protection for bacteria and algae and in return they provide the sponge with food. Sponges commercial use including bathing, padding and artistic uses.
MOVEMENT STRUCTURES/TYPE
All sponges are sessile, meaning they live attached to something their entire adult life. Their incurrent and excurrent pores move water.
BODY COVERING; CELL LAYERS; LEVEL OF ORGANIZATION; PROTECTION
Sponges are multicellular organisms with a diploblastic body wall that consists of an outer layer called the pinacoderm and an inner layer called choanoderm. They have a one cell layer epidermis. Their body wall contains numerous pores called ostia through which water enters in the body through a canal system into the central body cavity. Sponges also have openings called oscula through which water passes out from the body. Many sponge species contain toxic substances and spicules on the outside of their body to ward off predators, and are used during competition among other sponges or organisms to ensure their space in the ecosystem.
SUPPORT; MAINTAINING BODY SHAPE
Sponges have either radial symmetry or asymmetry. They are supported by a skeleton made up of the collagen protein and spicules, which may be calcareous or siliceous. The skeletal structure, choanocytes (collar cells), and other cells are in a gelatinous model called the mesohyl.
OBTAINING NUTRIENTS
Sponges have a unique feeding system in which they do not have mouths, but instead have tiny pores in their outer walls through which they filter food and nutrients from the incoming water currents created by the collar cells. They continuously filter water through their pores, the choanocytes ingest the food, and release the water back out. Poriferas lack gut and other digestive organs. The flow of water through the sponge is unidirectional, driven by the beating of flagella which line the surface of chambers connected by a series of canals. They feed on algae, protozoans, bacteria, etc.
RESPIRATION, CIRCULATION & EXCRETION
Sponges do not have distinct circulatory, respiratory, digestive and excretory systems. Their pore systems support all of these functions. Sponges’ cells absorb oxygen by diffusion from water into the cells, as water flows through the body, into which carbon dioxide and other waste products also diffuse. Circulation also takes place through diffusion with environment. Mesenchyme cells in some sponges transport substances. They eliminate waste from their body the same way they filter out water after obtaining the nutrients.
Sponges do not have distinct circulatory, respiratory, digestive and excretory systems. Their pore systems support all of these functions. Sponges’ cells absorb oxygen by diffusion from water into the cells, as water flows through the body, into which carbon dioxide and other waste products also diffuse. Circulation also takes place through diffusion with environment. Mesenchyme cells in some sponges transport substances. They eliminate waste from their body the same way they filter out water after obtaining the nutrients.
RESPONSE
Sponges do not have a nervous system, but some respond to substances in the water.
Sponges do not have a nervous system, but some respond to substances in the water.
REPRODUCTION
Sponges can reproduce both sexually and asexually and are hermaphrodites, although they have no reproductive organs. They reproduce asexually by means of external or internal budding (formation of gemmules) or by the disintegration of their body (fragmentation). Sexual reproduction occurs when a sponge releases male gametes into the water and are taken in by a neighboring sponge through their pores. The sperm is then captured by the collar cells which then transform into specialized cells that carry the spermatozoa to the eggs. The fertilized egg then develops into a blastula which is then released into the water either right away, or after some development takes place inside the parent, depending on the species.
Sponges can reproduce both sexually and asexually and are hermaphrodites, although they have no reproductive organs. They reproduce asexually by means of external or internal budding (formation of gemmules) or by the disintegration of their body (fragmentation). Sexual reproduction occurs when a sponge releases male gametes into the water and are taken in by a neighboring sponge through their pores. The sperm is then captured by the collar cells which then transform into specialized cells that carry the spermatozoa to the eggs. The fertilized egg then develops into a blastula which is then released into the water either right away, or after some development takes place inside the parent, depending on the species.