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The animal kingdom is considered “monophyletic,” meaning it has a
single common ancestor.
Porifera is thought to be a “dead
end” clade, meaning no other
forms are evolved from them and
they remain much as they have
been for millions of years.
Basic Body Form of Sponges
Sac-like structure consisting of 3 parts:
1. epidermal cells
2. specialized cells
3. amoeboid cells
Sponges have no true tissues.
However, they do have
specialized (differentiated) cells
which perform specific
functions important to the
survival of the entire organism.
CollarChoanocyte
Ameobocyte
• collar: microvilli net that filters food
particles
• choanocyte: beats flagellum and
ingests trapped food particles
• ameobocyte: aka mesenchyme cells,
serve multiple functions
phagocytosis
distribute food and oxygen using
pseudopods
sclerocytes: produce spicules
chromocytes: produce pigments
archeocytes: undifferentiated cells
(stem cells)
food particles
food vacuole
Leuconoid Sponges
Complex structure.
Highly branched and folded.
Increased surface area.
Allows for larger organism.
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