meaning "pore bearer"

G ROUP 36: J ESSICA P ENNEY , T ONIKA Y OUNG L EVY , A ND K RISTEN

Evolutionary History

 Previously assigned to a separate subkingdom, Parazoa  Closest single-celled relatives are thought to be choanoflagellates  Does not form a monophyletic group  Fossil records of sponges have been found from about 580 million years ago  Archaeocyathids were a type of coralline sponge  ~5000 known species; ~150 freshwater species

Basic Characteristics

 Cellular-level organization  Body support (“skeleton”) provided by spicules  Filter feeders through pores  Either radially symmetrical or asymmetrical  Spicules and potential biotoxin for defence  Adults are sessile; larvae are motile  Reproduction:  Hermaphrodites  Sexual ; Asexual

Structure

 Body is divided into three layers:  The outermost layer comprised of pinacocytes  The middle layer, mesohyl  The innermost layer, choanocytes     Pinacocytes (Epidermal cells) Choanocytes (Collar cells) Mesohyl (Semi-fluid matrix) Water flow

A SCONOID S YNCONOID L EUCONOID

Classification

 Phylum Porifera  Class Calcarea  Class Demospongiae  Class Hexactinellida

Class Calcarea

 About 400 described species in this group  Exclusively marine; shallower, sheltered waters less than 1000m  Tropical regions associated with the coral reefs  Members of this group have large structural spicules  Skeletons made of calcite  Mainly dull, some colorful

Class Demospongiae

 Contain the largest number of species with 4750 species organized into 10 orders  Marine environment; intertidal to the abyssal zone; some species inhabit freshwater  Silicate spicules or spongin fibers or both within their soft tissues  Brightly colored

Class Hexactinellida

 Glass sponges  Depths between 200 and 1000m  Abundant in the Antartic  Upright stature  Skeleton made entirely of silica

• • • • • http://animaldiversity.ummz.umich.edu/site/accounts/information/Porifera.html

http://en.wikipedia.org/wiki/Sponge#Evolutionary_history http://course1.winona.edu/mdelong/Invertebrate/Porifera.pdf

http://www.buzzle.com/articles/porifera-characteristics.html

http://palaeos.com/metazoa/porifera/porifera.htm

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