Sponges● invertebrates● radial symmetry or are asymmetrical● multicellular but no cell specialization● living in fresh and marine waters
Internal● spongocoel: central cavity ○ covered with choanocytes ■ flagellated cell with a collar; generate water currents and collars trap food particles● osculum: larger openings● spicule: ○ a needle-like structure or part, such as on of the mineral structures, supporting the soft tissue of certain invertebrates
Nervous System● sponges do not have a nervous system; no brain, no nerve cells● nerve net ○ a diffuse network of neurons that conducts impulses in all directions from a point of stimulus● touch or pressure to the outside of a sponge will cause a local contraction of its body.
Respiration and Circulation● through its pores with canals that move the water to all throughout the sponge; then the oxygen from the water is used.
How Sponges Eat (Digestion)● Sponges are characterized by the possession of a feeding system unique among animals.● Poriferans dont have mouths; instead, they have tiny pores in their outer walls through which water is drawn.● Cells in the sponge walls filter bacteria from the water as the water is pumped through the body and out other larger openings.● 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.● Heterotrophic● Suspension feeders
● In all cases, poriferans have a canal system, through which they pump water.● Water enters through pores called ostia, flows through canals to a chamber called a spongocoel, and finally exits through large openings called oscula.
Excretion● A sponge has carbon dioxide and other wastes removed as the water moves in and out through the pores.
Reproduction● reproduces by budding and also sexually● hermaphorodites: individual functions as both male and female in sexual reproduction by● producing sperm and eggs.● dioecious: having the male and female reproductive organs in seperate individuals.● eggs: archeocytes (totipotent cells that have the ability to divide and produce al the differentiated cells in an organism) or choanocytes● sperm: choanocytes
Three Distinct Groups● Hexactinellida● Demospongia● Calcarea
Hexactinellida● glass sponges● viewed as an early branch within Porifera● much of their tissues are syncitia, extensive regions of cytoplasm● possess a unique system for rapidly conducting electrical impulses across their bodies, allowing them to react quickly to external stimuli
Demospongia● most diverse sponge group● tend to be large● brightly colored● reproduce both sexually and asexually● harvested by divers, then bleached and marketed to be sold as bath sponges
Calcarea● mainly live in the tropics● mainly found in shallow waters● small and dull in color
Carnivoruos Sponges● from the family Cladorhizidae● they capture small crustaceans with their spicules● spicule: ○ a needle-like structure or part, such as on of the mineral structures supporting the soft tissue of certain invertebrates, especially sponges.● cells migrate to the organism● digestion takes place extracellularly