Kingdom Animalia – Nematoda Phylum nematoda – round worms (~50,000 species, or more?); general characteristics: Very, very, very, very, very, very, common!!! One study found 90,000 nematordes in a single rotting apple. Maybe we’ll check this one out for ourselves in next weeks lab !! Another study found 236 different species in about 6.7 cc of coastal mud!! Triploblastic, bilateral, vermiform, un-segmented, pseudocoelomates Body round in cross section and covered by a layered cuticle; growth in juveniles usually accompanied by molting Have complete gut Have no specialized circulatory or gas exchange structures, and only longitudinal muscles. Why do you think they need a substrate to live in? Can be free-living or parasitic
Kingdom Animalia – Nematoda Parasitic example: Heart worms… cool eh?
Kingdom Animalia – Nematoda Whereas cnidarians and platyhelminthes did not have a body cavity (coelom), nematodes do. It is however a pseudocoelom. All the other animals that we discuss from now on will have true coelom (including us!). What is the advantage of having a coelom? * Note that in this picture, blue represents ectoderm, yellow represents endoderm, and red represents mesoderm. Green is the mesoglea which is not a true tissue…
Kingdom Animalia – Phylum Annelida Phylum Annelida – segmented worms (~12,000 species) - general characteristics: Bilaterally symmetrical, segmented worms with a true coelom Digestive tract complete, usually with regional specializaiton Closed circulatory system Nervous system well developed Marine, terrestrial, and freshwater species exist Include earthworms, marine polychaetes, and leaches
Kingdom Animalia Evolution of the coelom (body cavity):
Kingdom Animalia – Phylum Annelida Generally speaking, annelids are a very diverse group, particularly the marine polychaetes which may have highly developed appendages.
Kingdom Animalia – Annelid Classification Class Polychaeta – include most of the marine and freshwater annelids… these worms are often very well developed, having specialized appendages for feeding and/or swimming called setae or parapodia…
Kingdom Animalia – Annelid Classification Class Oligochaeta – earthworms and other similar freshwater annelids. have no setae or parapodia…
Kingdom Animalia – Annelid Classification Class Hirudinida – leeches… complex reproductive systems, hermaphroditic, most most are freshwater or marine (a few are semi-terrestrial). Ectoparasitic, they can be predaceous or scavenging… These animals have specialized suckers to help them attach to their “prey”… They also produce anesthetics and anticoagulation chemicals… Why do you think this is?
Time for a cool animal!! – 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…
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….
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.
Kingdom Animalia – Phylum Mullusca Generalized mulluscan body:
Kingdom Animalia –Mullusc Diversity Class Gastropoda – 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.
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?
Kingdom Animalia –Mullusc DiversityClass Polyplacophora - chitons 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?
Kingdom Animalia –Mullusc DiversityClass Bivlavia 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.
Kingdom Animalia –Mullusc DiversityClass Cephalopoda 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… and… they seem to be very good at “solving problems”…