Invertebrate Biology PDF

The Invertebrates Key Concepts Ctenophores: The Earliest Animals Porifera: The Sponges Radiata: Jellyfish and Other Radially Symmetric Animals Lophotrochozoa: The Flatworms, Rotifers, Bryozoans, Brachiopods, Mollusks, and Annelids Ecdysozoa: The Nematodes and Arthropods Deuterostomia...

The Invertebrates Key Concepts Ctenophores: The Earliest Animals Porifera: The Sponges Radiata: Jellyfish and Other Radially Symmetric Animals Lophotrochozoa: The Flatworms, Rotifers, Bryozoans, Brachiopods, Mollusks, and Annelids Ecdysozoa: The Nematodes and Arthropods Deuterostomia: The Echinoderms and Chordates A Comparison of Animal Phyla 2 Ecdysozoa A cuticle provides support and protection Allows colonization of dry environments Functions like an external skeleton & skin both Named for ecdysis – molting – of the cuticle to allow for growth. Some species undergo metamorphosis Internal fertilization Allows colonization of dry environments 3 Phylum Nematoda Roundworms In nearly all habitats from poles to tropics Over 25,000 species (more undiscovered) Tough collagen cuticle covers body Longitudinal but not circular muscles Pseudocoelom acts as hydrostatic skeleton and circulatory system Parasites, decomposers & tiny predators 4 Phylum Nematoda II Reproduction usually sexual with separate males and females Females generally larger than males Internal fertilization Caenorhabditis elegans – model organism Large number of species parasitic in humans and other vertebrates Ascaris lumbricoides – over 1 billion people infected Necator americanus – hookworm Enterobius vermicularis – pinworm (causes anal itching) Wuchereria bancrofti – causes elephantiasis 5 Phylum Arthropoda Perhaps most successful phylum 3/4 of all described living species Success related to body plan that permits them to live in all major biomes Exoskeleton made of chitin and protein Can be extremely tough or soft and flexible Provides protection, point of muscle attachment Relatively impermeable to water 6 The Arthropod Body Plan Segmented with jointed appendages for locomotion, food handling, or reproduction Tagmata – fused body segments Well developed sensory organs for sight, touch, smell, hearing, and balance Compound eyes – ommatidia Some species also have simple eyes (ocelli) Sophisticated brain consists of cerebral ganglia connected to several smaller ventral ganglia 7 The Arthropod Body Plan Open circulatory system Gas exchange occurs via gills or tracheal system with spiracles Complex digestive system with mouth, crop, stomach, intestine, and rectum Excretion – metanephridia or Malpighian tubules 8 Main Arthropod Subphyla Subphyla and examples (est. Class characteristics number of species) Chelicerata: spiders, scorpions, Body usually with cephalothorax and mites, ticks, horseshoe crabs, abdomen only; six pairs of appendages, and sea spiders (74,000) including four pairs of legs, one pair of fangs, and one pair of pedipalps; terrestrial; predatory or parasitic Myriapoda: millipedes and Body with head and highly segmented centipedes (13,000) trunk. In millipedes, each segment with two pairs of walking legs; terrestrial; herbivorous. In centipedes, each segment with one pair of walking legs; terrestrial; predatory, poison jaws. Hexapoda: insects such as Body with head, thorax, and abdomen; beetles, butterflies, flies, fleas, mouthparts modified for biting, chewing, grasshoppers, ants, bees, sucking, or lapping; usually with two pairs wasps, termites, and of wings and three pairs of legs; mostly springtails (>1 million) terrestrial, some freshwater; herbivorous, parasitic, or predatory Crustacea: crabs, lobsters, Body of two to three parts; three or more shrimp (45,000) pairs of legs; chewing mouthparts; usually marine 9 Subphylum Chelicerata Three living classes Arachnida (Spiders, scorpions, ticks, and mites) Merostomata (horseshoe crabs) Pycnogonida (sea spiders) Two sections – cephalothorax and abdomen Six pairs of appendages Chelicerae Pedipalps Walking legs (four pairs) 10 Spiders Fangs (chelicerae) are supplied with venom from poison glands Partially digest prey in place by injecting digestive fluid Abdominal spinnerets produce silk Used to wrap prey, construct egg sacs, and spin webs 11 Other Chelicerates Scorpions Pedipalps modified into claws Abdomen tapers into a stinger used to inject venom Bear live young Mites and ticks Two main body segments are fused Many mites are free-living decomposers Ticks are vertebrate ectoparasites 12 Subphylum Myriapoda Class Diplopoda – millipedes 2 pairs of legs per segment, herbivorous Class Chilopoda – centipedes 1 pair of legs per segment, carnivorous a: David Aubrey/The Image Bank/Getty b: Larry Miller/Science Images Source 13 Subphylum Hexapoda More insect species than all other animal species combined Wings crucial to success – outgrowths of body wall Separate sexes with internal fertilization Metamorphosis Complete – 4 stages, adult and larval stages very different Incomplete – 3 stages, young resemble miniature adults Complete is most common – don't compete for resources with young 14 Features causing diversity of insects 35 orders – differences in wings and mouthparts (mandibles and maxillae) More insect species than all other animal species in total Wings crucial to success – outgrowths of body wall Did not have to give up legs to grow wings Mouthparts highly variable to allow a wide range of diets 15 Major Orders and Characteristics of Insects: Part 1 Order and examples Order characteristics (approx. number of described species) Coleoptera: beetles, Two pairs of wings (front pair thick and leathery, acting weevils (400,000) Illustrations of as wing cases, and back pair membranous); armored a beetle. exoskeleton; biting and chewing mouthparts; complete metamorphosis; largest order of insects Lepidoptera: Two pairs of colorful wings covered with tiny scales; long butterflies, moths Illustrations of tubelike tongue for sucking; complete metamorphosis; (150,000) a butterfly. larvae are plant-feeding caterpillars; adults are important pollinators Hymenoptera: ants, Two pairs of membranous wings; chewing or sucking bees, wasps (130,000) Illustrations of mouthparts; many have posterior stinging organ on a ant. females; complete metamorphosis; many species social; important pollinators Diptera: flies, One pair of wings with hind wings modified into halteres mosquitoes (120,000) (balancing organs); sucking, piercing, or lapping Illustrations of a mosquito. mouthparts; complete metamorphosis; larvae are grublike maggots found in various food sources; some adults are disease vectors Hemiptera: true bugs; Two pairs of membranous wings; piercing or sucking 16 Major Orders and Characteristics of Insects: Part 2 Order and examples Order characteristics (approx. number of described species) Orthoptera: crickets, Two pairs of wings (front pair leathery, back pair grasshoppers (20,000) Illustrations of a membranous); chewing mouthparts; mostly grasshopper. herbivorous; incomplete metamorphosis; powerful hind legs for jumping Odonata: damselflies, Two pairs of long, membranous wings; chewing dragonflies (5,500) mouthparts; large eyes; predatory on other insects; Illustrations of a dragonfly. incomplete metamorphosis; nymphs aquatic; considered early-diverging insects Phthiraptera: sucking Wingless ectoparasites; sucking mouthparts; flattened lice (3,000) Illustrations of a body; reduced eyes; legs with clawlike tarsi for clinging sucking lice. to skin; incomplete metamorphosis; very host-specific; vectors of typhus Siphonaptera: fleas Wingless, laterally flattened; piercing and sucking (2,400) Illustrations of a mouthparts; adults are bloodsuckers on birds and flea. mammals; jumping legs; complete metamorphosis; vectors of plague 17 Subphylum Crustacea Crabs, lobsters, barnacles and shrimp Marine, fresh water, and terrestrial May be predators, scavengers, or filter feeders Nauplius larva very different from adult 18 Subphylum Crustacea Unique in having two pairs of antennae Mandibles, maxillae and maxillipeds Walking legs and swimmerets First pair of walking legs may be modified into claws Carapace may extend over cephalothorax 19 GQs Finish the chapter! Echinoderms and Chordates