Chapter 26: Animals the Invertebrates

Chapter 26: Animals – The InvertebratesGeneral Characteristics of Animals  Multicelled  In most cases cells form tissues that become arranged as organs and organ systems  Body cells of nearly all species have diploid chromosome number  Heterotrophs  Require oxygen for aerobic respiration  Reproduce sexually and asexually  Most animals are motile during at least part of their life cycle  Stages of embryonic development  Embryonic cells give rise to primary tissue layers ectoderm, endoderm, and mesodermDiversity in Body Plans  Vertebrates – animals with backbone  Invertebrates – no backbone  Animals are radial or bilateral  Radial Symmetry – body parts arranged regularly around a central axis  Bilateral Symmetry – right and left halves are mirror images of each other.  Gut – a tubular or saclike region in the body in which food is digested then absorbed.  Saclike guts - have one opening (mouth) for taking in food and expelling wastes  Tubelike guts - have 2 openings (mouth and anus) a complete digestive system  Body cavity – between gut and body wall  Coelom – unique tissue lining called peritoneum  This lining also encloses organs and helps hold them in place (diaphragm)  Some invertebrates don’t have a body cavity and tissues fill this region  Pseudocoel (false coelom) – a body cavity with no peritoneum  Segmented animals have a repeating series of body units  They may or may not be similar to one anotherPuzzles About Origins  Animals originated between 1.2 billion and 670 million years ago  Probably evolved from protistans Sponges – Success in Simplicity  Sponges (Porifera) – animals with no symmetry tissues or organs  Most live in marine  Body of a sponge is not symmetrical  Made of spongin - a protein and the sharp glasslike spicules are made of calcium carbonate or silica  Water flows into the sponge body through microscopic pores and chambers  Collar cells – line inner body and beat flagella to move water through. Food particles get trapped in microvilli  Reproduce sexually  Release sperm into water  Some reproduce asexually  Fragmentation – small fragments break away from the parentCnidarians – Tissues Emerge  Cnidarians – tentacled, radial animals  Most live in seas  Nematocysts – capsules that house dischargeable tubular, threads  Some deliver toxins  Some deliver a sticky ooze to entangle prey  Body Plans  Medusae  Float  Look like bells or upside-down saucers  Mouth centered under bell  May have extensions to help with feeding and capture prey  Polyps  Tubelike body with a tentacle-fringed mouth at one end  Other end attached to substrate  Epithelium – a tissue having a free surface that faces the environment  Nerve cells – in epithelium and these cells receive signals to detect changes in surroundings  Contractile cells – carry out response by shortening  Hydrostatic Skeleton – any fluid-filled cavity or cell mass against which contractile cells can act.Various Stages in Cnidarian Life Cycles  Some species, Obelia, Physalia, etc, include both polyp and medusa body forms  Medusa is the sexual stage  Has gonads – primary reproductive organs  Releases gametes by rupturing (lysis)  Planulas – a zygote that is a swimming or creeping larva  Forms into a polypComb Jellies  Radial symmetry  Weak – swimming predators in plankton communities  Eight rows of comblike structures made of thick fused cilia  Do not produce nematocystsAcoelomate Animals – And The Simplest Organ Systems  When we move beyond cnidarians in our survey, we find animals that range from flatworms to humans. All of these animals have simple or complex organs  Organ – an association of one or more kinds of tissues arranged in particular proportions and patterns  Organ System – two or more organs that are interacting efficiently in the performance of some taskFlatworms (Platyhelminthes)  Turbellarians, flukes, tapeworms  Bilateral  Simple organ systems in a flattened body  Saclike gut  Most are hermaphrodites – have female and male gonads  Has a penis so two flatworms can reproduce sexually by exchanging sperm  Tubellarians  Live in seas, planarians live in freshwater  Eat tiny animals or suck tissues from dead or wounded ones  A planarian can divide in half and regenerate missing parts  Reproduce asexually by transverse fission  Flukes  Parasitic worms  Life cycle has sexual and asexual phases  One to four hosts  Tapeworms  Parasitize intestines of vertebrates  Scolex – attach to intestine wall and has suckers, hooks or both  Ribbon Worms  Bilateral  Soft-bodied elongated predators  Swallow or suck tissue fluids from small worms mollusks and crustaceans  Shallow marine habitatsRoundworms (Nematoda)  Pseudocoelomate worms  Thrive in nearly all environments  Most abundant animals alive  20,000 known species  bilateral  cuticles – a tough, flexible body covering  simplest animal with a complete digestive system  parasitic species can severely damage their hosts, humans, cats, dogs, cows, sheep, soybeans  help decompose and recycle nutrientsRotifers (Rotifera)  bilateral  false coelom  most live in freshwater  eat bacteria and microscopic algae  have a pharynx, esophagus, digestive glands, stomach, intestine, anus  a crown of cilia at the head end  two “toes”Two Major Divergences  Protostomes  Spiral cleavage  First infolding forms mouth  Archenteron – is an internal cavity that the tissues split at sides to form coelum  Ex. Mollusks, annelids, arthropods  Deuterostome  Radial cleavage  First infolding forms anus  Archenteron – an internal cavity that the outpouching forms coelum  Ex. Echinoderms, chordates A Sampling of Molluscan Diversity  Have fleshy soft bodies  Bilateral  Have a small coelom  Most have a shell  Mantle –  Most mollusks have a fleshy foot  Chitons – slow moving with dorsal shell divided into eight plates  Bivalves – two shells, clams, oysters, mussels  Cephalopods – squids, octopus  Octopuses have a highly developed nervous system with a large complex brainTwisting and Detwisting of Soft Bodies  Soft snail body  Its anus dumps wastes near the mouth  As the gastropod embryo develops a cavity between its mantle and shell twists  Torsion – twisting of internal organsHiding Out One Way or Another  A shell is an advantage against predators  Dig into sand to hideOn the Cephalopod Need For Speed  Cephalopods lost their thick external shell and became streamlined and active  Nerves connect their brain to muscles that respond swiftly to food or danger  Jet Propulsion – force a jet of water from mantle cavity and a funnel-shaped siphonAnnelids – Segments Galore  Bilateral and segmented  Phylum name means “ringed forms”  Setae – bristles on each side of segments  Provide traction to move through dirt  Earthworms (oligochaetes) have few setae  Leeches have no setaeAdvantages of Segmentation  Individual parts can undergo modification and become highly adapted for specific tasksAnnelid Adaptations – A Case Study  Earthworms  Partitions divide their body into a series of coelomic chambers  Gut extends through all chambers  Has a cuticle but it is permeable to water as well as to gases (have to live in moist habitats)  Scavengers  Aerate soil and lift nutrients to surfaceArthropod  Trilobites (extinct)  Chelicerates – spiders  Crustaceans – barnacles and crabs  Uniramians – centipedes, millipedes, insects  Arthropod means jointed footAdaptations of Insects and Other Arthropods  Hardened exoskeleton  Cuticle of chitin, proteins, surface waxes and calcium carbonate  Exoskeleton – protective external skeleton  Defense against predation  Waxy surface restricts water evaporation  Molting – periodic shedding of body structures that are too small, worn out or both  Jointed Appendages  Cuticle is thinner at joints for motility  Led to appendages as diverse as wings, antennae and legs  Fused and Modified Segments  Many fused together segments are modified to perform more specialized functions  Different segments fused to form 3 regions – head, thorax and abdomen  Respiratory Structures  Aquatic arthropods depend on gills  Insect tracheas begin as pores on the body surface and branch into tubes that deliver oxygen directly to tissues  Specialized Sensory Structures  Many species have a wide angle of vision and can process visual information from many directionsDivision of Labor  Many species divide the job of surviving and reproducing among different stages of development  Juvenile – a miniaturized version of the adult  Metamorphosis – body form changes from embryo to adult  Adult stage specializes in dispersal and reproductionA Look At Spiders and Their Kin  Chelicerates originated in shallow seas  Marine species – mites, sea spiders, horseshoe crab  Land species – spiders, scorpions, ticks, chigger mites (arachnids)  Spiders and scorpions are predators  Bites of ticks can transmit disease  Mites are free-living scavengers  Arachnids have segments fused into forebody and hindbody  Forebody – 4 pairs of legs, 1 pair pedipalps (sensory), 1 pair of chelicerae that inflict wounds and discharge venom  Hindbody – spin silk threads  Open circulatory system – a heart that pumps blood into body tissuesA Look At The Crustaceans  Shrimp, lobsters, crabs, barnacles, pillbugs  Have an exoskeleton  Majority live in marine habitats  Many have 16 – 20 segments  2 pairs of antennae  1 pair of jawlike appendages (mandibles)  molt repeatedly How Many Legs  millipedes  have about 100 legs  each segment has 2 pairs of legs  scavenge decaying plants  centipedes  have 15-177 pairs of legs  each segment has 1 pair of legs  fast-moving aggressive predators outfitted with fangs and venom glands  prey on insects earthworms snailsA Look At Insect Diversity  have a head, thorax, and abdomen  3 pairs of legs  2 pairs of wings usually  most successful insects are…  small in size  great reproductive capacity  are winged  life cycle proceeds through stages that allows for exploitation of different resources  nymphs – small versions of the adult  larvae – maggots specialized for eating  pupa (cocoon) – an enclosure  metamorphosis – a dramatic change in body form  our most aggressive competitors, they destroy crops, wool, paper, etc.The Puzzling Echinoderms  feather star, sea urchin, sea cucumber, brittle stars, sea biscuits, sand dollars  coelomate deuterostomes  usually have a complete digestive tract  adults are radial symmetry  body wall bears a number of spines, plates made of calcium carbonate  have no brain  water-vascular system – system of canals that delivers water throughout the body. By redistributing water they can move Chapter 26: Animals – The InvertebratesGeneral Characteristics of Animals In most cases cells form tissues that become arranged as organs and organ systems Body cells of nearly all species have ______chromosome number Require oxygen for aerobic respiration Most animals are motile during at least part of their life cycle Embryonic cells give rise to primary tissue layers ectoderm, endoderm, and mesodermDiversity in Body Plans Vertebrates –  Invertebrates –  Animals are radial or bilateral Radial Symmetry –  Bilateral Symmetry –  Gut – a tubular or saclike region in the body in which food is digested then absorbed. Saclike guts –  Tubelike guts –  Body cavity –  Coelom –  This lining also encloses organs and helps hold them in place (diaphragm) Some invertebrates don’t have a body cavity and tissues fill this region Pseudocoel (false coelom) –  Segmented animals have a repeating series of body units They may or may not be similar to one anotherPuzzles About Origins Animals originated between 1.2 billion and 670 million years ago Probably evolved from ______Sponges – Success in Simplicity Sponges (Porifera) –  Body of a sponge is not ______ Made of spongin –  Water flows into the sponge body through microscopic pores and chambers Collar cells –  Reproduce sexually Some reproduce asexually Fragmentation – Cnidarians – Tissues Emerge Cnidarians –  Most live in ______ Nematocysts –  Some deliver ______ Some deliver a sticky ooze to entangle prey Body Plans Medusae Look like bells or upside-down saucers May have extensions to help with feeding and capture prey  Polyps Other end attached to substrate Epithelium –  Nerve cells –  Contractile cells –  Hydrostatic Skeleton – Various Stages in Cnidarian Life Cycles Some species, Obelia, Physalia, etc, include both polyp and medusa body forms Medusa is the sexual stage Has gonads –  Releases gametes by rupturing (lysis) Planulas –  Forms into a polyp Comb Jellies ______symmetry Weak –  Eight rows of comblike structures made of thick fused cilia Do not produce ______Acoelomate Animals – And The Simplest Organ Systems When we move beyond cnidarians in our survey, we find animals that range from flatworms to humans. All of these animals have simple or complex organs Organ –  Organ System – Flatworms (Platyhelminthes) Turbellarians, flukes, tapeworms Simple organ systems in a flattened body  Most are hermaphrodites –  Has a penis so two flatworms can reproduce sexually by exchanging sperm Tubellarians Live in ______, planarians live in ______ Eat tiny animals or suck tissues from dead or wounded ones  A planarian can divide in half and ______missing parts Reproduce asexually by transverse fission Flukes Life cycle has sexual and asexual phases Tapeworms Scolex –  Ribbon Worms Soft-bodied elongated predators Swallow or suck tissue fluids from small worms mollusks and crustaceansRoundworms (Nematoda) Thrive in nearly all environments Most abundant animals alive ______known species  Cuticles –  Simplest animal with a ______digestive system Parasitic species can severely damage their hosts, humans, cats, dogs, cows, sheep, soybeansRotifers (Rotifera) Most live in ______ Eat bacteria and microscopic algae Have a pharynx, esophagus, digestive glands, stomach, intestine, anus A crown of ______at the head endTwo Major Divergences Protostomes First infolding forms ______ Archenteron –  Ex.  Deuterostome First infolding forms ______ Archenteron – an internal cavity that the outpouching forms coelum Ex. A Sampling of Molluscan Diversity Have fleshy soft bodies Have a small ______ Mantle –  Most mollusks have a ______ Chitons – Bivalves –  Cephalopods –  Octopuses have a highly developed nervous system with a large complex brain Twisting and Detwisting of Soft Bodies Soft snail body As the gastropod embryo develops a cavity between its mantle and shell twists Torsion – Hiding Out One Way or Another A shell is an advantage against predators Dig into sand to hideOn the Cephalopod Need For Speed Cephalopods lost their thick external shell and became streamlined and active Nerves connect their brain to muscles that respond swiftly to food or danger Jet Propulsion – Annelids – Segments Galore Phylum name means ______ Setae –  Provide traction to move through dirt ______(oligochaetes) have few setae ______have no setae Advantages of Segmentation Individual parts can undergo modification and become highly adapted for specific tasksAnnelid Adaptations – A Case Study Earthworms Partitions divide their body into a series of ______chambers Gut extends through all chambers Has a cuticle but it is permeable to water as well as to gases (have to live in moist habitats)Arthropod Trilobites (extinct) Chelicerates –  Crustaceans –  Uniramians –  Arthropod means ______Adaptations of Insects and Other Arthropods Hardened exoskeleton Cuticle of ______, proteins, surface waxes and calcium carbonate Exoskeleton –  Defense against predation Waxy surface restricts water evaporation Molting –  Jointed Appendages Cuticle is thinner at joints for motility Led to appendages as diverse as ______, ______and ______ Fused and Modified Segments Many fused together segments are modified to perform more specialized functions Different segments fused to form 3 regions – head, thorax and abdomen Respiratory Structures Aquatic arthropods depend on ______ Insect tracheas begin as pores on the body surface and branch into tubes that deliver oxygen directly to tissues Specialized Sensory Structures Many species have a wide angle of ______and can process visual information from many directions Division of Labor Many species divide the job of surviving and reproducing among different stages of development Juvenile – Metamorphosis –  Adult stage specializes in dispersal and reproductionA Look At Spiders and Their Kin Chelicerates originated in shallow seas Marine species –  Land species –  Spiders and scorpions are ______ Bites of ticks can transmit disease Mites are free-living scavengers Arachnids have segments fused into ______and ______ Forebody – 4 pairs of legs, 1 pair pedipalps (sensory), 1 pair of chelicerae that inflict wounds and discharge venom Hindbody –  Open circulatory system –A Look At The Crustaceans Have an ______ Majority live in marine habitats  Many have 16 – 20 segments 2 pairs of ______ 1 pair of jawlike appendages (mandibles)How Many Legs Millipedes Each segment has _____ pairs of legs Scavenge decaying plants Centipedes Each segment has _____ pair of legs Fast-moving aggressive predators outfitted with fangs and venom glands Prey on insects earthworms snailsA Look At Insect Diversity Have a head, thorax, and abdomen _____ pairs of legs _____ pairs of wings usually  Most successful insects are… Life cycle proceeds through stages that allows for exploitation of different resources Nymphs –  Larvae –  Pupa (cocoon) –  Metamorphosis – a dramatic change in body form Our most aggressive competitors, they destroy crops, wool, paper, etc.The Puzzling Echinoderms Feather star, sea urchin, sea cucumber, brittle stars, sea biscuits, sand dollars Usually have a ______digestive tract Adults are ______symmetry Body wall bears a number of spines, plates made of calcium carbonate Water-vascular system –

Chapter 26: Animals the Invertebrates

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