Phylum Porifera The Sponges Taxonomy Kingdom Animalia Subkingdom
Phylum – Porifera The Sponges
Taxonomy • Kingdom – Animalia • Subkingdom – Parazoa (lacks tissues) • Phylum – Porifera (pores)
Characteristics o Simplest of all animals o Most ancient (540 my) o Contain specialized cells but no other organization level o Most are marine
Characteristics o Saltwater sponges are brightly colored (5, 00010, 000 species) o Freshwater sponges are small and dull green color (150 species) o Size – 2 meters to 2 cm
Characteristics o Porifera means porebearing o Water enters through pores (porocytes or ostia) bringing in food and oxygen o Filter feeders on plankton o Osculum – large opening at the top where excess water leaves
Characteristics o Gas exchange done by diffusion o No nervous system o Some can produce toxins or poison for protection o Two body layers: outer epidermis and inner endodermis
Characteristics o Radial or Asymmetrical o Sessile as adults (attach to rocks) o Free-swimming larval stage called Parenchymula o Also reproduce by fragmentation (pieces break off & form a new sponge)
WATER OUT Water Flow Through the Sponge WATER IN Osculum
Water Flow Through Sponge The movement of water through the sponge provides a simple mechanism for feeding, respiration, circulation, and excretion.
Sponge Body Structure o Inside body cavity of sponge is hollow o Called the Spongocoel o Have 2 cell layers: § Outer epidermis § Inner endoderm (gastrodermis) o Jelly-like material between cell layers called mesenchyme (mesohyl)
• Choanocytes (collar cells) line the gastrovascular cavity & capture food • Amebocytes (archaeocytes) digest & distribute food
Choanocytes • Have flagella that spins to pull in water & food • Collar traps plankton (food) from water • Oxygen and waste products are transported into and out of the sponge by water currents Collar
Other Specialized Cells o Amebocytes: • Pick up food from choanocytes • Finish digestion • Move through the mesenchyme & take food to other cells
Skeletal Structure of the Sponge • Skeleton made of network of protein fibers called Spongin- soft protein fibers • Spicules are hard spear or starshaped structures; often stick out of sponge; offer protection • Spicules made of Ca. CO 3 (limestone) or silica (glass) • Most species have a combo to spongin and spicules
Sponge Skeletons Silica Spicules Limestone Spicules SPONGIN
Sponge Skeletons SPICULES VENUS FLOWER BASKET
Sponge Reproduction o Sponges can regenerate (regrow) lost body parts through mitotic cell division (asexual) o Sponges also reproduce asexually by budding
Sponge Reproduction o Sponges are hermaphrodites (produce both eggs & sperm) o Sponges reproduce sexually by releasing eggs & sperm into the water from the Osculum o Cross-fertilize each other’s eggs o Have internal fertilization Sponge releasing eggs & sperm
Surviving Harsh Conditions o Gemmules are specialized buds made to survive harsh weather (hot, cold, dry, etc. ) o Contain food, amebocytes and a protective covering of spicules o Released when a sponge dies o Resist dessication (drying out) o Become adult sponge when conditions become favorable again
Ecology of Sponges o Provide habitats for other aquatic life o Example of commensalism (other organisms benefit, sponge not affected) o Form relationships with photosynthetic organisms o Example of mutualism (both benefit)
Classification of Phylum Porifera • Class Calcarea: spicules of calcium carbonate, all marine; Ex: Sycon • Class Hexactinellida: siliceous spicules, often cylindrical shaped, all marine; Ex: Euplectella (Venus flower basket) • Class Demospongiae: siliceous spicules or spongin or both, fresh and marine; Ex: Spongilla and all bath sponges
Sycon
Euplectella “Venus’ flower basket”
Spongilla
Branching Tube Sponge
Stove Pipe Sponge
Vase Sponges
Barrel Sponges
Ball Sponges
Rope Sponges
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