Arthropods, Echinoderms, and Chordates Bi 10 10/22/2013 Revised Schedule Friday, Nov. 22: Chapter 17, Part 2 Chapter 15, 16 Reading Quiz Due Wednesday, Nov. 27: Special Lecture: Review + World s Weirdest Fungi (NO LAB) ESSAY 3 Outline Due Chapter 17 Reading Quiz Due December 4: Chapter 18, LAB PRACTICAL December 6: Chapter 21, LAB PRACTICAL Chapter 18, 21 Reading Quiz Due, December 13: Lecture Final Exam, Essay 3 Due, Last Study Guides Due, Extra Credit Museum Trip Due Take a Wild Guess About how many insects are there for every single person on earth? That is to say, by what factor do insects outnumber us? 1
Adaptations of Animal Phyla Specialized cells for eating Organized tissues Bilateral symmetry True coelom (body cavity) Segmentation Notochord/spine Tissue Layers Most animals have three layers of tissue. Ecto = outer. Ectoderm = outer skin. Makes the skin and nerves. Meso = middle. Mesoderm makes the muscles. Endo = inside. Endoderm makes the gut. Pocket lined by mesoderm is called a coelom. Arthropods: Segmented Invertebrates with Jointed Exoskeletons Arthropods are the most successful animal group on Earth. Most animals are arthropods! They have a hard, jointed shell called an exoskeleton. What are some advantages and disadvantages of having an exoskeleton with specialized segments? 2
Arthropods: Millipedes and Centipedes Millipedes are among the earliest land animals, and used to grow up to a meter long! Scavengers, vegetarians. Diplopods two pairs of legs per segment. Centipedes are predators. The front legs are modified into venomous fangs. Contrary to the text, some can deliver a painful bite. Arthropods: Class Arachnida Four pairs of legs (1), plus special claws/ feelers for grasping food. Two segments: thorax/head fused (2) and abdomen (3). How can you tell an arachnid apart from an insect? Mouthparts Arthropods: Subphylum Crustacea Have 3+ pairs of legs and a larva that usually looks different from the adult. Close relatives of insects! Note specialized feeding mouthparts and legs. Fiddler crab larvae Fiddler crab adult Isopod ( same legs ) Copepod (tiny crustacean) Krill (also tiny) Lobster 3
Arthropods: Class Insecta Have 3 pairs of legs no more, no fewer. 3 segments: head, thorax, abdomen. Most successful group of animals on Earth! Insect Diversity A small sample of the diversity of insects on earth: Beetles cover their soft inner wings with hard outer wings. Bugs suck up their food, and tend to have crossed wings. Ants and wasps have two pairs of gauzy wings Insects play many critical roles, including decomposition, pollination of flowering plants, predation, and being a food source for other animals! 4
Adaptations of Animal Phyla Specialized cells for eating Organized tissues Bilateral symmetry True coelom (body cavity) Segmentation Notochord/spine Phylum Echinodermata Echinoderm means spiny-skinned. Aquatic animals with near-radial symmetry as adults and bilateral symmetry as larvae. Vascular system uses water, not blood! Like us, they have an endoskeleton (skeleton inside). Phylum Chordata This is our phylum! It includes the vertebrates, animals with backbones. The backbone develops from a simpler structure called a notochord. The notochord comes from mesoderm, and helps protect the spinal cord. 5
Echinoderms and Chordates vs. Other Animals In most animals the hole made when the blastula folds in becomes the mouth. In both echinoderms and chordates, the hole made when the blastula folds in becomes the anus. This is one of the clues that echinoderms are our sister phylum (cousins)! Chordate Subphyla Not all chordates have vertebrae, or even bones! Tunicates Lancelets Vertebrates Chordate Adaptations Different classes of chordates evolved many adaptations to life on land. Jaws and backbone Tetrapod (four-footed) limbs Amniotic sac (in egg or inside mother) 6
Cartilaginous vs. Bony Fish Fish are the most successful vertebrates on earth in terms of species count. Icthyos = fish. Class Chondryichthyes = cartilaginous fish, like sharks. Osteichthyes = bony fish. Includes ray-finned fish Know that sharks have cartilaginous skeletons, while rayfinned fish have bony skeletons! Class: Amphibia First tetrapods. Legs evolved from lobed fins of fish. Need to live near water; lay eggs in water and breathe through lungs and skin. Class: Reptilia Evolved amniote egg, which can be laid on land without drying out. (Mammals are also amniotes.) Reptiles, like amphibians, are ectotherms except for birds, which are endotherms! 7
Class: Mammalia Give birth to live young (except for monotremes), have hair, lactate milk. (Monotremes secrete it from fur, not nipples.) Marsupial mammals (~5% of mammals) give birth to poorly developed young and keep them in a pouch. Placental mammals have longer pregnancies and no pouch. Class Mammalia, Order Primates Review: Chordate Adaptations Different classes of chordates evolved many adaptations to life on land. Jaws and backbone Tetrapod (four-footed) limbs Amniotic sac (in egg or inside mother) 8