Topic 21: Porifera and Cnidaria Flashcards
Phylum Porifera
basal animals that lack true tissues are informally known as sponges.
Except for a motile larval stage, sponges are _____
sessile
do sponges have true tissues
no
Spicules
provide structural support to sponges (hard needles or rods of silica or calcium carbonate that maintain shape and structure of the sponge)
spongin
Some sponges have only a fibrous collagen-protein network for support
four simple sponge cell types
Porocytes, Choanocytes, Epidermal cells, amoebocytes
Epidermal cells
the outer layer consists of tightly packed epidermal
cells.
Porocytes
tubular cells that make up the pores of a sponge
Choanocytes (collar cells)
line the spongocoel. They generate a water current through the sponge and ingest suspended food. Bring
oxygen and nutrients to the sponge while also removing waste and carbon dioxide
amoebocytes
Mobile amoebocytes are found in the mesohyl where they transport nutrients to other cells of the sponge body, produce materials for skeletal fibres (spicules), or differentiate into other cell types as needed
mesohyl (“middle matter”)
The body of a sponge consists of two layers of cells (epidermis and the choanocyte layer) separated by a gel-like, non-cellular matrix, the mesohyl (“middle matter”) that helps maintain the shape and structure of the sponge. Mesohyl contains mobile amebocytes
and skeletal elements (spicules or spongin) deposited by the amebocytes
Sponges are _____ feeders
suspension (capturing food particles suspended in water passing through their body)
Water is drawn (by beating of choanocyte flagella) through ______ into a cavity called ____ and out through an ____
pores (ostia)
spongocoel
opening (osculum)
do sponges have gonads?
no
are sponges hermaphrodites?
yes
Zygotes retained until they develop into ______
motile ciliated larvae
Sponges also reproduce asexually by
fragmentation and by budding.
Eumetazoa.
all animals but sponges (animals with true tissues)
basal Eumetazoa are two phyla:
Ctenophora and Cnidaria
Phylum Cnidaria
- one of the oldest descendants of clade Eumetazoa.
Cnidaria body plan
- a simple diploblastic, radial body plan
- The basic body plan of cnidarians is a sac with a central digestive compartment, the gastrovascular cavity
Cnidarian body plan two variations
polyp (sessile form) and medusa (motile jellyfish)
How do cnidarians feed
predators that use tentacles to capture prey and are armed with cnidocytes
cnidocytes
explosive cells that function in defense and capture of prey and contain nematocysts
nematocysts
Cnidocytes contain complex secretory organelles called nematocysts that can deliver a sting to other organisms
Two major clades of cnidaria
Clade Medusozoa and anthozoa (polyps)
Clade Medusozoa are also called
Hydrozoans
Hydrozoans
alternate between polyp and medusa forms
Clade Medusozoa
the predominant stage in the life cycle of most
scyphozoans (“true jellyfish”) and cubozoans (box jellyfish).
Clade Anthozoa
includes the corals and sea anemones and occur only as polyps
