Porifera The Sponges
General Characteristics “Pore-bearer” Sessile 9000 species Mostly marine, some fresh water Range from mm to meters Acoelomate Ectothermic Not metameric Filter feeders-up to 1500 L/day
Symmetry and Shape Often asymmetrical Can have radial symmetry Ball, vase, disc, shrub, tree
Development Neither protosome or deuterosome Doesn’t have mouth or anus Diploblastic vs. Triploblastic No tissues Specialized cells
Skeleton Spicules Needle-like Spongin Mainly collagen
Specialized Cells 3 cell layers Pinacoderm Mesohyl Choanoderm
Pinacoderm Outer layer Cells are pinacocytes (Flat) Porocyte (ostia) is opening for water
Mesohyl Gelatinous middle layer Amoebocytes Archeocytes Reproduction Spicule formation Transport and store food Archeocytes
Choanoderm Inner layer Choanocytes Nutrient absorption Beating flagella create current Possibly from choanoflagellates Nutrient absorption
Ascon Simplest Least common Porocyte -> spongocoel -> osculum
Sycon Folded walls Porocyte -> incurrent canal -> radial canal -> spongocoel -> osculum
Leucon Loss of spongocoel Multiple oscula Porocyte -> incurrent canal ->radial canal -> excurrent canal -> osculum
Sexual Reproduction Monoecious Release gametes through osculum Larva settles and develops Sperm transported by amoebocytes Fertilization in mesohyl
Asexual Reproduction Fragmentation Budding Gemmules
Uses and Importance Spongin used in sponges Food source for snails, sea stars, fish Protection for small fish