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Transcript
Invertebrates
Invertebrates
•
•
•
•
Major Phyla
Porifera = Sponges
Cnidarians = Jellyfish
Mollusks = Squids,
clams, snails
• Annelids =
Earthworms, leeches
• Arthropods = insects,
crustaceans
Phylum Porifera
• AKA: Sponges
• Most primitive animals
(>570myo)
– Related to subgroup of
animal-like protista
• ~9000 species (most
saltwater)
• Sessile (stationary)
• Reproduction:
– Sexual: egg and sperm
released into water
• Larva attaches to surface
and grows into sessile
adult
– Asexual: Budding
Sponge Structure
• Filter feeders:
– Water sucked in through
many pores
– Water exits through osculum
• Bodies made of 2 cell layers
– No body symmetry
– Pinacocytes (Outer layer):
Flat, protective cells
– Collar Cells (Inner layer): cells
with cilia to create current
• Specialized Cells
– No tissue, organs, or systems
– Amoebocytes: digest and
transport nutrients around
the body
Phylum Cnidaria
• Basic Characteristics
• Radial symmetry
• Two body forms:
– 1) Polyps: tubes with mouth and tentacles facing upward
– 2) Medusa: Umbrella-shaped with mouth and tentacles
downward
Phylum Cnidaria
• Reproduction
– Asexual: Budding
– Sexual: Sperm and egg
released into water; new
polyp created
• Anatomy
– 2 tissue layers
(evolutionary
advancement)
• 1) Ectoderm (outer layer):
covered with stinging cells
• 2) Endoderm (inner layer)
• Gastrovascular cavity:
single opening to digest
food