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Animal Bio - Metazoans and Songes
key points of metazoans and sponges
28
Biology
Undergraduate 2
04/09/2012

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Term
In bigger metozoans what limits cell size?
Definition
surface area to volume ratio issues
Term
What is the major advantage to being multicellular?
Definition
diversification of activities: different cells do different things
Term
Choanoflagellates
Definition
solitary or colonial aquatic eukaryotes that have a beating flagellum surrounded by a collar of microvilli that collect bacteria

they strongly resemble sponge feeding cells so people believe they might be a sister group to sponges
Term
What grade of organization do porifera (sponges) have?
Definition
cellular
Term
What type of symmetry do sponges have?
Definition
Assymetrical
or superficial radial symmetry
Term
Spicules
Definition
form the rigid skeleton of a sponge
either calcareous or siliceous
Term
Collagen fibrils in the intercellular matrix
Definition
form the fibrous portion of the sponge
Term
Calcarea
Definition
have calcium carbonate spicules with one, three or four rays
Term
Hexactinallida
Definition
6-rayed with siliceous spicules
Term
Demospongiae
Definition
siliceous spicules, spongin or both
95% of sponge species
Term
Homoscleromorpha
Definition
lack a skeleton, or have siliceous spciules without an axial filament
Term
Mesohyl
Definition
a gelatinous matrix/connective tissue that sponge cells are arranged in
Term
Pinacocytes
Definition
line the outer surface and form the pinacoderm
Can perform phagocytosis
mildy contractile, so they affect the shape of the sponge
Can be modified as myocytes/porocytes to form bands arounds pores to help regulate flow of water
Term
Archaeocyte
Definition
move about the mesohyl
can specialize for reproduction, secreting skeletal elements, food transport and storage
Term
Choanocytes
Definition
blow the mesohyl, linning the inner chambers with one end embedded in the mesohyl
- collar of microvilli connected by microfillaments surrounds flagellum and forms a fine filtering device to strain food
Term
Sclerocytes
Definition
make spicules
Term
Spongocytes
Definition
make spongen
Term
Collencyte
Definition
make collagen
Term
In general, how do sponges eat?
Definition
they collect particles from water pumped through internal canals which have dermal pores called ostia
Term
How do choanocytes aid in feeding?
Definition
they collect food particles using flagella collar cells (a form of suspension feeding)
- the beating flagella keep the current flowing
-they trap and phagocytize passing food particles into food vacuoles, where digestion starts
- Partially digested food passes to specialized archaeocyte s(aka amoebocytes) for distribution through the body
Term
How do pinacocytes aid in feeding?
Definition
They may also phagocytize food particles at the sponge surface
Term
Asconoid canal system
Definition
Their spongocoels is flagellated
- simplest system --> small and tube shaped
- water enters via ostia, exits via osculum
Term
What are the disadvantages to the asconoid canal system?
Definition
- limited surface area for food collection
- limited size and shape
- no advantage to being big, because if you were big you'd miss everything in the spogocoel
Term
Syconoid canal system
Definition
Flagellated Canals
- their body wall has choanocyte-lined radial canals that empty into the spongocoel
- water enters via PROSOPYLES and exits via APOPYLES into the spongocoel and out the osculum

folding in their surface areas means that most of the water passing through is accessible
Term
Leuconoid canal system
Definition
Flagellated Chambers
- largest, most complex sponges
- Water enters incurrent canals via multiple ostia, and go to chambers with choanocytes
Water leaves via excurrent canals

Advantage: the high surface to volume ratio --> can filter all water present, meeting food demands
Term
Asexual reproduction in sponges
Definition
Somatic embryogenesis : new sponges form from fragments

Bud formation - individuals break off and form new colonies
or by internal buds
Term
Gemmule
Definition
an internal bud
created by a collection of archaeocytes that collect in teh meshyl and are then coated with spongin and spicules (they survive very extreme temperatures)
Cells escape the gemmule through a MICROPYLE and develop into new sponges
Term
parenchymula
Definition
the free swimming larva of sponges
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