1. Phylum: Porifera The Sponges

2. Phylum Porifera • Belongs to Parazoa (beside the animals) • Evolved from colonial protozoans • Evolutionary “dead end” • Most primitive animals

3. Sponges come in many colors…

4. Phylum Porifera General characteristics: • pore-bearing animals • sessile • most are marine • asymmetrical •  5,000 species

5. Porifera General Construction • “one hole sac” • central cavity = spongiocoel • water enters through ostium • water exits through osculum • filter feeders: algae, bacteria, organic debris

6. Porifera Anatomy • choanocytes or collar cells- create water currents for circulation & feeding • spicule-skeletal element for support • amoebocyte-transport of nutrients from choanocytes to non-feeding cells • mesenchyme-gelatinous protein colloid; not a cellular layer

7. Anatomy of a Sponge

9. Porifera Reproduction • Asexual – budding, regeneration, gemmules • Sexual- sperm and ova arise from ameobocytes or choanocytes • Sponges are monoecious (one house) which is a reference to both sperm and ova production by a single organism

10. Classification of sponges Based on spicule type: • Calcium spicules – CaCO3 (calcium carbonate); chalk sponges • Silicon spicules – Si3O2; glass sponges • Spongin spicules – organic or horny; natural commercial sponges

12. Classification of sponges Based on canal system: • Ascon – simplest 2 layer sac; Leucosolenia • Sycon – surface is folded to increase surface area; Grantia • Leucon – most advanced & successful; permits maximum surface & size; surface deeply folded to form systems of canals; commercial sponges

14. D. Class Calcarea (Calcispongiae) • 1. These are calcareous sponges with spicules of calcium carbonate. • 2. The spicules are straight or have three or four rays. • 3. Most are small sponges with tubular or vase shapes. • 4. Asconoid, syconoid and leuconoid forms all occur.

15. E. Class Hexactinellida (Hyalospongiae) • 1. These are glass sponges with six-rayed spicules of silica. • 2. Nearly all are deep-sea forms; most are radially symmetrical.

16. F. Class Demospongiae • 1. This class contains 95% of living sponge species. • 2. Spicules are siliceous but not six rayed; they may be absent or bound together by spongin. • 3. All are leuconoid and all are marine except for Spongillidae, the freshwater sponges.