Kingdom Animalia – Phylum Mullusca

1. Kingdom Animalia – Phylum Mullusca Phylum Mullusca – snails, slugs, clams, oysters, squids, octopus, etc. (> 50,000 species – maybe up to 100,000??) General characteristics: Bilaterally symmetrical (or secondarily asymmetrical), coelomate Well developed organ systems Have mantle with shell glands that secrete calcareous epidermal spicules, shell plates, or shells Have large, well defined muscular foot, often with a flattened creeping sole, (in squids and octopus, the foot is modified into tentacles / arms.

3. Kingdom Animalia – Phylum Mullusca Generalized mulluscan body:

4. Kingdom Animalia –Mullusc Diversity Gastropods – slugs, snails, and nudibranchs Not all gastropods have shell (blue). There is a high level of variation amongst different shells; why do you think this is? How do you think nudibranchs that do not have any Shells defend themselves? Most gastropods have a large, fleshy foot which is used for locomoation (green) Most gastropods have a unique file-like mouth part called the radula (orange). Herbivorous forms use it for grazing, carnivorous forms have modified it into a drill, or a harpoon that can inject toxins into their prey. Most gastropods have gills for gas exchange.

5. Kingdom Animalia –Mullusc Diversity - Gastropods Snail: What do you think is the function of this shell? Nudibranch: How do you think this animal defends itself?

6. Kingdom Animalia –Mullusc Diversitychitons Chitons also have a large foot (green) that is used for locomotion and clamping down on rocks; gills (yellow) for gas exchange; a shell made up of 7 or 8 individual plates (blue); and a radula (orange) specialized for grazing on algae and some encrusting invertebrates. What do you think is the advantage of having multiple (7 or 8) shell plates?

7. Kingdom Animalia –Mullusc Diversitybivlaves Bivalves have two shells, hinged along One edge, with the animal in between (blue). Most bivalves use their gills (yellow) for both gas exchange, as well as for food capture. How do you think this may work? The foot (green) of some bivalves is reduced, While in others, it is specialized for digging. Here is a picture of a clam. Bivalves also include mussels, oysters, and scallops.

8. Kingdom Animalia –Mullusc DiversityCephalopods Cephalopods – octopus, squids, nautilus, and cuttlefish Cephalopods have generally modified their foot (green) into tentacles (arms) that allow them to manipulate potential prey items, as well as to move around their environments Their shells (blue) can be complete and external (nautilus), reduced and internal (squid), or completely non-existent (octopus). What is the advantage of each? Most cephalopods use gills (yellow) for gas exchange, and have a specialized beak (orange) for tearing food particles. Finally, most cephalopods use jet propulsion for movement and swimming…

9. Kingdom Animalia – Phylum Echinodermata Phylum Ehinodermata (spiny skin) – sea stars, brittle stars, sea cucumbers, sea urchins, sand dollars, etc. (~8,000 - 10,000 species) General characteristics: All echinoderms are marine All echinoderm adults have basic pentamerous radial symmetry derived from bilaterally symmetrical larvae Nervous system diffuse, decentralized, usually of a nerve net, nerve ring, and radial nerves. Have separate sexes, although hermaphroditic species do exist Have a water vascular system composed of a series of fluid-filled canals, usually evident externally as muscular podia

10. Kingdom Animalia – Phylum Echinodermata The water vascular system: Functions: Walking Gas exchange Sensory Food manipulation

11. Kingdom Animalia – Phylum Echinodermata The sea star grabs on to the mussel, pulls on the shell until there is an opening, then ejects its stomach into the mussel for digestion and absorption of the food.

12. Kingdom Animalia – Phylum Echinodermata Echinoderm diversity – Asteroids (sea stars): Ecologically very important carnivores. Have ability to regenerate arms. A lot more active than you may think…

13. Kingdom Animalia – Phylum Echinodermata Echinoderm diversity – Ophiroids (brittle stars): Very delicate, these brittle stars will readily lose their arms in order To avoid predation. There are carnivore, planktivore, and herbivore forms…

14. Kingdom Animalia – Phylum Echinodermata Echinoderm diversity – Holotheroids (sea cucumbers): Mostly detritavores, these animals defend themselves by toxins in their skin, but also by evisceration… how do you think that works?

15. Kingdom Animalia – Phylum Echinodermata Echinoderm diversity – Echinoids (sea urchins and sand dollars): These animals can be herbivores, carnivores, or planktivores. They are very common, and in some places, can play a major ecological role: e.g. off the coast of California, consider the relationship between sea urchins, sea otters, and kelp…

16. Kingdom Animalia – Phylum Tardigrada Phylum Trdigrada (water bears) ~ 400 – 500 species Free living or symbiotic, they are found all over… Tardigrades are known for their Anabiosis – state of greatly recuced metabolic activity during unfavorable conditions; and Cryptobiosis – an extreme state of anabiosis or dormancy where all external sings of metabolic activity are missing!! How tough are they? check it out…

17. Kingdom Animalia – Phylum Tardigrada Tartigrades have recovered from immersion in extremely toxic compounds such as brine, ether, absolute alcohol, and even liquid helium!! They have survived temperature ranging from +149 C to –272 C (almost at absolute zero!!) They have also survived high vacuums, intense ionizing radiation, and long periods with no environmental oxygen. Former Soviet zoologists claim that tardigrades survived experiments in outer space!! In one case, a 120 year old dried moss specimen from a museum was accidentally moistened, yielding living tardigrades!!! ….. You get the picture….

18. Kingdom Animalia – Phylum Chordata Major Characteristics found in all chordates: 1. Notochord – a stiff but flexible rod along the length of the body 2. Dorsal hollow nerve chord – neural structure that develops into the brain and and central nervous system 3. Pharyngeal gill slits – openings or grooves found on the cavity behind the mouth (found in all chordates at least at some stage of their life cycle) 4. Post-anal tail Chordates include two invertebrate groups including lancelets and tunicates, and one vertebrate group that is further subdivided into different groups of fish, amphibians, reptiles, birds, and mammals. You are responsible for all the text material on chordates – p434 to p445.