Chapter 33 - Introduction to Invertebrates Flashcards
What are invertebrates?
animals that lack a backbone
What phylum are sponges in?
Porifera
What are filter feeders?
aquatic animals that capture food particles suspended in the water that passes through their body
What is the cavity where water is drawn through pores in filter feeders?
spongocoel
What is the opening to the spongocoel that water flows out of?
osculum
What characteristic of most animals do sponges lack?
tissues
What are choanocytes?
flagellated collar cells in sponges that generate a water current and ingest suspended food
What is the mesohyl layer?
a gelatinous noncellular layer between two cell layers of a sponge
What are amoebocytes?
totipotent cells found in the mesohyl that play roles in digestion and manufacture of skeletal fibers
What does totipotent mean?
Totipotent cells can become any cell at any time.
What are hermaphrodites?
each individual functions as both male and female; ex. sponges
What clade are animals with true tissues in?
Eumetazoa
Name the characteristics of Cnidarians.
sessile and motile; diploblastic; radial; sac-like with gastrovascular cavity; single opening; carnivores that use tentacles to capture prey
What the gastrovascular cavity?
a central digestive compartment
What is a polyp?
a sessile Cnidarian that adheres to the substrate by the aboral end of its body
What is a medusa?
a motile, free-swimming Cnidarian that has a bell-shaped body with its mouth on the underside
What are cnidocytes?
cells unique to Cnidarians that function in defense and capture of prey; have nematocysts
What are nematocysts?
organelles of cnidocytes that eject a stinging thread
What part of the cnidarians act as a hydrostatic skeleton?
the gastrovascular cavity
What do hydrostatic skeletons do?
allow contractile fibers to move against
What two clades did Phylum Cnidaria diverge into?
Medusozoa and Anthozoa
What do Medusozoans include?
all cnidarians that produce a medusa including scyphozoans, cubozoans, and hydrozoans
What are hydras?
freshwater cnidarians that exist only in polyp form and reproduce asexually by budding
