NEM 10V Lecture Notes - Lecture 27: Nematology, Spongin, Osculum
Nematology
Invertebrates:
Part 1 Porifera (Sponges):
• Invertebrates-animals without backbones.
• Animals-are multicelled, heterotropic eukaryotes with unwalled cells.
• Sponges are in a Phylum called Porifera
-notable characteristics are being multicellular with specialized cells, but not so
specialized as to have tissues
-asymmetrical- cannot divide the body into halves that are mirror images.
-Sponges feed by filtering food from large quantities of water pumped in through small
pores called ostium, and out through a larger central opening called an osculum.
• Flagellated choanocytes, also called collar cells, create the flow of water and trap and
digest the passing food particles.
• Sponges are hermaphrodites, meaning they produce both eggs and sperm.
• The sperm are released into the water, while the eggs are retained in the body where they
are fertilized.
• Larvae are released, find a location to settle down, and then become sessile, meaning the
adult sponge will stay in one location for the rest of its life.
• Some groups of sponges secrete fibrous proteins called spicules that provide structural
support.
Multicellular?
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