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