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Invertebrates: Phylum Porifera – The Sponges. Introduction to Kingdom: Animalia. The ocean is where life is thought to have once evolved. And of that life, animals are the most diverse kingdom in appearance Animals are heterotrophic , eukaryotic , and multicellular and lack cell walls.
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Introduction to Kingdom: Animalia • The ocean is where life is thought to have once evolved. And of that life, animals are the most diverse kingdom in appearance • Animals are heterotrophic, eukaryotic, and multicellular and lack cell walls. • 95% = invertebrates (do not have backbone)5% = vertebrates (have a backbone)
Invertebrates: Spongesphylum porifera • Sponges are best described as aggregations of specialized cells • Do not form true tissues • Simplest multicellular animals • Nearly all are marine • All are sessile (permanently attached to substrate)
Invertebrates: Sponges • Sponges are suspension feeders (filter feeder) • As sponges get larger, they need structural support. Most have spicules, transparent siliceous or calcareous supporting structures of different shapes and sizes. (Mercedes Benz shape…) • Many also have tough elastic fibers made of a protein called spongin
Anatomy of a Sponge • Outer surface is covered with flat cells called pinacocytes and occasional tube-like pore cells (porocytes) through which a microscopic canal allows water to enter. • Water is pumped into a larger feeding chamber line with collar cells (choanocytes) • Each collar cells has a flagellum the creates currents and traps food particles. • Water then exits through a large opening on top of the sponge – osculum. • Sponges are sexual and asexual reproducers and some are hermaphrodites.
Biology of sponges • Sponges benefit some marine animals by providing a habitat • Some sponges are green because they have photosynthetic organisms in their tissues • Many sponges protect themselves from predators by producing toxins • Some biologists believe sponges evolved independently from all other animals • Some sponges live on the seafloor and some on lake bottoms
Commercial use of sponges • Large species of the class Demospongia are harvested for commercial use • Their dried spongin skeletons can hold as much as 35 times their weight in liquid • Many Greek sponge fishers emigrated to Tarpon Springs, Florida, where their descendants still fish the sponge beds off the Florida coast.
Commercial use of sponges • It takes approximately 5 years for a sponge in the wild to reach a marketable size (12.5 cm / 5 in.) and it will retail for about $10.00 • Sponges may also prove to be sources of novel medications for fighting disease. • A chemical called cytosine arabinoside blocks DNA synthesis in tumors and is used in the treatment of cancer. • Sponges also produce antibacterial chemicals that are being studied.
