Chapter 33 Invertebrates PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Fig. 33-3a A sponge
Fig. 33-3b A jelly
Fig. 33-3e 1.5 mm Acoel flatworms (LM)
Fig. 33-3f A marine flatworm
Fig. 33-3g A rotifer (LM)
Fig. 33-3i A brachiopod
Fig. 33-3l A ribbon worm
Fig. 33-3m An octopus
Fig. 33-3n A marine annelid
Fig. 33-3p A priapulan
Fig. 33-3q 100 µm Tardigrades (colorized SEM)
Fig. 33-3r An onychophoran
Fig. 33-3s A roundworm
Fig. 33-3t A scorpion (an arachnid)
Fig. 33-3v A sea urchin
Fig. 33-3w A tunicate
Phylum Porifera (sponges): are basal animals that lack true tissues Sponges live in both fresh and marine waters Sponges are attached (sessile) organisms Sponges lack true tissues and organs Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia 18
Sponges are suspension feeders, capturing food particles suspended in the water that pass through their body Choanocytes, flagellated collar cells, generate a water current through the sponge and ingest suspended food Water is drawn through pores into a cavity called the spongocoel, and out through an opening called the osculum 19
Sponges consist of a noncellular mesohyl layer between two cell layers Amoebocytes are found in the mesohyl and play roles in digestion and structure Reproduction: Most sponges are hermaphrodites: Each individual functions as both male and female 20
Amoebocytes and choanocytes produce male and female gametes Sperm flows out of sponge with water, but eggs remain in mesophyl Fertilization occurs in mesophyl and produces zygote. Zygote forms flagellated larva Larva flow out of sponge with water and find suitable surface on which to develop into an adult 21
Fig. 33-4 Anatomy of a sponge Choanocyte Osculum Flagellum Collar Food in mucusparticles Choanocyte Azure vase sponge (Callyspongia plicifera) Spongocoel Phagocytosis of food particles Amoebocyte Porocytes Epidermis Mesohyl Water flow Amoebocytes
Phylum Cnidaria : cnidarians are an ancient phylum of eumetazoans Phylum Cnidaria is one of the oldest groups in this clade Cnidarians have diversified into a wide range of both sessile and motile forms including jellies, corals, and hydras They exhibit a relatively simple diploblastic, radial body plan Cnidarians have simple contractile and nervous tissues 23
Fig. 33-UN2 Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
The basic body plan of a cnidarian is a sac with a central digestive compartment, the gastrovascular cavity A single opening functions both as mouth and anus There are two variations on the body plan: the sessile polyp and motile medusa 25
Fig. 33-5 Polyp and medusa forms of cnidarians Polyp Mouth/anus Tentacle Gastrovascular cavity Medusa Gastrodermis Body stalk Mesoglea Epidermis Tentacle Mouth/anus
Cnidarians are carnivores that use tentacles to capture prey The tentacles are armed with cnidocytes, unique cells that function in defense and capture of prey Nematocysts are specialized organelles within cnidocytes that eject a stinging thread 27
Fig. 33-6 Tentacle Cuticle of prey Thread Nematocyst Trigger Thread discharges Cnidocyte Thread (coiled)
four Phylum Cnidaria is divided into major classes: Hydrozoa Scyphozoa Cubozoa Anthozoa 29
Table 33-1
Fig. 33-7 Cnidarians (b) Jellies (class Scyphozoa) (c) Sea wasp (class Cubozoa) (d) Sea anemone (class Anthozoa) (a) Colonial polyps (class Hydrozoa)
Class Hydrozoa Most hydrozoans alternate between polyp and medusa forms 32
Fig. 33-8-3 The life cycle of the hydrozoan Obelia 1 mm Feeding polyp Reproductive polyp Portion of a colony of polyps Medusa bud ASEXUAL REPRODUCTION (BUDDING) Developing polyp Gonad MEIOSIS Medusa Egg SEXUAL REPRODUCTION Planula (larva) Sperm FERTILIZATION Zygote Key Haploid (n) Diploid (2n) Mature polyp
Classes Scyphozoa, Cubozoa, and Anthozoa In the class Scyphozoa, jellies (medusae) are the prevalent form of the life cycle In the class Cubozoa, which includes box jellies and sea wasps, the medusa is boxshaped and has complex eyes Cubozoans often have highly toxic cnidocytes Class Anthozoa includes the corals and sea anemones, which occur only as polyps 34
Lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms Bilaterian animals have bilateral symmetry and triploblastic development The clade Bilateria contains Lophotrochozoa, Ecdysozoa, and Deuterostomia Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia } Bilateria 35
Lophotrochozoa include such major phyla as: Platyhelminthes (flatworms), Rotifera (rotifers), Mollusca (mollusks), and Annelida (segmented worms) 36
Phylum Platyhelminthes (flatworms) Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats Platyhelminthes (flatworms) are acoelomates They are flattened dorsoventrally and have a gastrovascular cavity 37
Flatworms main classes are: Turbellaria (mostly free-living flatworms) Trematoda (trematodes, or flukes) Cestoda (tapeworms) 38
Table 33-2
Class Turbellaria Turbellarians are nearly all free-living and mostly marine animals The best-known turbellarians are commonly called planarians Planarians have mouth on ventral surface, which can act as anus Pharynx is a muscular tube ending in mouth Planarians release digestive juice onto prey and suck food particles into gastrovascular 40 cavity, where they complete digestion
Fig. 33-9 A marine flatworm (class Turbellaria)
Planarians have light-sensitive eyespots on anterior end (head region) The planarian nervous system is more complex and centralized than the nerve nets of cnidarians and include two ganglia (collection of nerve cells ) located in head and ventral nerve cords (nerve fibers extending from ganglia for the length of the body Planarians are hermaphrodites and can reproduce sexually, or asexually through fission (pinching in two segments) 42
Fig. 33-10 Pharynx Gastrovascular cavity Mouth Eyespots Ganglia Ventral nerve cords
Class Trematoda (flukes) Trematodes live as parasites in or on other animals They parasitize mostly vertebrates, and their larval stage parasitize invertebrates as intermediate host Trematodes that parasitize humans spend part of their lives in snail hosts 44
Fig. 33-11 Reproduction of trematodes Male he life cycle of blood fluke Schistosoma ansoni), a rematode Human host Female 1 mm Motile larva Ciliated larva Snail host
Class Cestoda (tapeworms) Tapeworms are parasites of vertebrates and lack a digestive system Tapeworms absorb nutrients from the host s intestine Tapeworms have larval stage occurring in an invertebrate or vertebrate intermediate host Fertilized eggs, produced by sexual reproduction, leave the host s intestinal tract in feces and then develop into larvae Larvae infect intermediate host and if transferred to final host, develop into adult 46
Fig. 33-12 Scolex: anterior end with suckers and hooks used to attach to intestinal lining of host Proglottids: body segments containing reproductive organs 200 µm Proglottids with reproductive structures Hooks Sucker Scolex
Phylum Rotifera Rotifers, phylum Rotifera, are tiny animals that inhabit fresh water, the ocean, and damp soil Rotifers are smaller than many protists but are truly multicellular and have specialized organ systems 48
Fig. 33-13 Jaws Crown of cilia Anus Stomach 0.1 mm
Rotifers have an alimentary canal, a digestive tube with a separate mouth and anus that lies within a fluidfilled pseudocoelom Rotifers reproduce mainly by parthenogenesis, in which females produce offspring from unfertilized eggs Asexual reproduction: partenogenetic offspring are females only Some species are unusual in that they lack males entirely Sexual reproduction: parthenogenetic offspring are males and females; then males fertilize eggs produced by females 50
Phylum Mollusca (mollusks) Phylum Mollusca includes terrestrial, marine and freshwater animals, such as snails and slugs, oysters and clams, and octopuses and squids Mollusks are soft-bodied animals, but most are protected by a hard shell Mollusks are coelomates Nephridia: excretory organs Alimentary canal: mouth, esophagus, stomach, intestines, anus Nervous system: nerve ring and ventral nerve cords 51
All mollusks have a similar body plan with three main parts: Muscular foot Visceral mass (internal organs) Mantle (tissue fold over visceral mass; produces shell) Many molluscs also have a water-filled mantle cavity, and feed using a rasplike radula Open circulatory system: hemolymph pumped by heart to short arteries emptying into sinuses surrounding organs 52
Closed circulatory system Vertebrates, and a few invertebrates, have a closed circulatory system. Closed circulatory systems have the blood closed at all times within vessels of different size and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does not normally fill body cavities. Open circulatory system The open circulatory system is common to molluscs and arthropods. Open circulatory systems (evolved in crustaceans, insects, mollusks and other invertebrates) pump blood into a hemocoel with the blood diffusing back to the circulatory system between cells. Blood is pumped by a heart into the body cavities, where tissues are surrounded by the blood. 53
Nephridium Visceral mass Heart Mantle Coelom Gonads Intestine Mantle cavity Anus Stomach Shell Radula Mouth Gill Foot Nerve cords Nerve ring Esophagus Mouth Radula Most molluscs have separate sexes with gonads located in the visceral mass, but also can be hermaphrodites
Major classes of molluscs: Gastropoda (snails and slugs) Bivalvia (clams, oysters, and other bivalves) Cephalopoda (squids, octopuses, cuttlefish, and chambered nautiluses) 55
Table 33-3
Chitons Class Polyplacophora consists of the chitons, oval-shaped marine animals encased in an armor of eight dorsal plates 57
Class Gastropoda About three-quarters of all living species of molluscs are gastropods (b) A sea slug (a) A land snail Video: Nudibranchs 58
Most gastropods are marine, but many are freshwater and terrestrial species Most have a single, spiraled shell Slugs lack a shell or have a reduced shell Their anus and mantle cavity are located near the head, due to torsion of visceral mass during development Head with eyes on tentacles 59
Fig. 33-18 Mantle cavity Anus Stomach Intestine Mouth
Class Bivalvia Molluscs of class Bivalvia include many species of clams, oysters, mussels, and scallops They have a hinged shell divided into two halves; no head or radula The mantle cavity of a bivalve contains gills that are used for feeding as well as gas exchange Incurrent and excurrent siphon Palp pushes food toward mouth 61
Fig. 33-19
Fig. 33-20 Digestive gland Mouth Mantle Hinge area Gut Coelom Heart Adductor muscle Anus Excurrent siphon Shell Palp Foot Mantle cavity Gonad Gill Water flow Incurrent siphon
Class Cephalopoda Class Cephalopoda includes squids and octopuses, carnivores with beak-like jaws surrounded by tentacles of their modified foot Beak may excrete toxins into prey Close circulatory system Shell: external, internal, or absent Cephalopods have brain and sensory organs Well expressed eyes 64
Fig. 33-21 Octopus Squid Squids use their siphon to fire a jet of water, which allows them to swim very quickly Chambered nautilus
Phylum Annelida (segmented worms) Annelids have bodies composed of a series of fused rings The phylum Annelida is divided into three classes: Oligochaeta (earthworms and their relatives) Polychaeta (polychaetes) Hirudinea (leeches) 66
Class Oligochaeta Oligochaetes are named for relatively sparse chaetae, bristles made of chitin They include the earthworms and a variety of aquatic species Earthworms eat through soil, extracting nutrients as the soil moves through the alimentary canal (mouth, pharynx, crop, gizzard, intestines, anus) Earthworms are hermaphrodites but crossfertilize Video: Earthworm Locomotion 67
Class Oligochaeta Oligochaetes have two layers of muscle in body wall: Longitudinal, and Circular Oligochaetes are coelomates: coelom is divided by septa between segments Closed circulatory system (dorsal and ventral vessels connected by pairs of segmented vessels) Metanephridia: excretory organs 68
Class Oligochaeta Nervous system: two cerebral ganglia with ventral nerve cords extending length of body Gas exchange occurs through the skin Reproduction: hermaphrodites; cocoon produced by clitellum Embryos develop in cocoon in the soil 69
Fig. 33-22 Epidermis Circular muscle Cuticle Coelom Septum (partition between segments) Longitudinal muscle Metanephridium Anus Dorsal vessel Chaetae Intestine Nephrostome Fused nerve cords Clitellum Ventral vessel Metanephridium Esophagus Crop Giant Australian earthworm Pharynx Intestine Cerebral ganglia Mouth Subpharyngeal ganglion Blood vessels Gizzard Ventral nerve cord with segmental ganglia
Leeches Members of class Hirudinea are blood-sucking parasites, such as leeches Leeches secrete a chemical called hirudin to prevent blood from coagulating 71
Fig. 33-24
Concept 33.4: Ecdysozoans are the most speciesrich animal group Ecdysozoans are covered by a tough coat called a cuticle The two largest phyla are nematodes and arthropods Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia 73
Phylum Nematoda (roundworms) Nematodes, or roundworms, are pseudocoelomates, and found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals They have an alimentary canal, but lack a circulatory system Reproduction in nematodes is usually sexual, by internal fertilization Some species of nematodes are important parasites of plants and animals 74
Fig. 33-26 Encysted juveniles Muscle tissue 50 µm Juveniles of the parasitic nematode Trichinella spiralis encysted in human muscle tissue (LM)
Phylum Arthropoda Coelomates Two out of every three known species of animals are arthropods Members of the phylum Arthropoda are found in nearly all habitats of the biosphere 76
General Characteristics of Arthropods The appendages of some living arthropods are modified for many different functions The body of an arthropod is completely covered by the cuticle, an exoskeleton made of chitin Ecdysis: when an arthropod grows, it molts its exoskeleton Arthropods have an open circulatory system and alimentary canal Nervous system: brain and ventral nerve cords Reproduction: sexual with separate sexes; internal fertilization 77
Fig. 33-29 Cephalothorax Abdomen Antennae (sensory reception) Head Thorax Swimming appendages (one pair located under each abdominal segment) Walking legs Pincer (defense) Mouthparts (feeding)
Major subphyla of Arthropods: Cheliceriformes (sea spiders, horseshoe crabs, scorpions, ticks, mites, and spiders) Myriapoda (centipedes and millipedes) Hexapoda (insects and relatives) Crustacea (crabs, lobsters, shrimps, barnacles, and many others) 79
Table 33-5
Cheliceriforms Cheliceriforms, subphylum Cheliceriformes, are named for clawlike feeding appendages called chelicerae 81
Fig. 33-31 Most modern cheliceriforms are arachnids, which include spiders, scorpions, ticks, and mites Scorpion Dust mite Web-building spider 82
Arachnids have an abdomen and a cephalothorax, which has six pairs of appendages, the most anterior of which are the chelicerae Gas exchange in spiders occurs in respiratory organs called book lungs Many spiders produce silk, a liquid protein, from specialized abdominal glands Pedipalps: paired appendages for sensing and feeding 83
Fig. 33-32 Intestine Stomach Digestive gland Heart Brain Eyes Ovary Poison gland Anus Spinnerets Silk gland Gonopore (exit for eggs) Book lung Sperm receptacle Chelicera Pedipalp
Myriapods Subphylum Myriapoda includes millipedes and centipedes Myriapods are terrestrial, and have jaw-like mandibles Millipedes, class Diplopoda, have many legs Each trunk segment has two pairs of legs 85
Centipedes, class Chilopoda, are carnivores They have one pair of legs per trunk segment 86
Fig. 33-33 A millipede They have two pairs of legs per trunk segment
Insects Subphylum Hexapoda, insects and relatives, has more species than all other forms of life combined They live in almost every terrestrial habitat and in fresh water The internal anatomy of an insect includes several complex organ systems Most insects have separate males and females and reproduce sexually 88
Fig. 33-35 Abdomen Thorax Head No cephalothorax! Compound eye Antennae Anus Heart Dorsal artery Cerebral ganglion Crop Vagina Malpighian tubules Ovary Tracheal tubes Nerve cords Mouthparts
Many insects undergo metamorphosis during their development In incomplete metamorphosis, the young, called nymphs, resemble adults but are smaller and go through a series of molts until they reach full size Insects with complete metamorphosis have larval stages known by such names as maggot, grub, or caterpillar The larval stage looks entirely different from the adult stage 90
Fig. 33-36 (a) Larva (caterpillar) (b) Pupa (c) Later-stage pupa Pupa transitional stage between larva and adult (d) Emerging adult (e) Adult
Crustaceans While arachnids and insects thrive on land, crustaceans, for the most part, have remained in marine and freshwater environments Crustaceans, subphylum Crustacea, typically have branched appendages that are extensively specialized for feeding and locomotion Most crustaceans have separate males and females and reproduce sexually 92
(a) Ghost crab Barnacles are a group of mostly sessile crustaceans They have a cuticle that is hardened into a shell (b) Krill (c) Barnacles
Concept 33.5: Echinoderms and chordates are deuterostomes Sea stars and other echinoderms, phylum Echinodermata, may seem to have little in common with phylum Chordata, which includes the vertebrates Shared characteristics define deuterostomes (Chordates and Echinoderms) Radial cleavage Formation of the mouth at the end of the embryo opposite the blastopore 94
Fig. 33-UN5 Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
Phylum Echinodermata Sea stars and most other echinoderms are slow-moving or sessile marine animals A thin epidermis covers an endoskeleton of hard calcareous plates Echinoderms have a unique water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion, feeding, and gas exchange Males and females are usually separate, and sexual reproduction is external 96
Fig. 33-39 Central disk Digestive glands Anus Stomach Spine Gills Madreporite Ring canal Gonads Radial nerve Radial canal Tube feet Ampulla Podium
(a) A sea star (class Asteroidea) (b) A brittle star (class Ophiuroidea) Echinoderms (c) A sea urchin (class Echinoidea) (d) A feather star (class Crinoidea) (e) A sea cucumber (class Holothuroidea) (f) A sea daisy (class Concentricycloidea)
Thank you for your attention and participation!
You should now be able to: 1. Describe how a sponge feeds and digests its food 2. List the characteristics of the phylum Cnidaria that distinguish it from other animal phyla 3. List main classes of Cnidaria and distinguish among them based on life cycle morphology 4. List the characteristics of Platyhelminthes and distinguish among the main classes 101
5. Describe the features of mollusks and distinguish among the main classes 6. Describe the features of annelids 7. List the characteristics of nematodes that distinguish them from other wormlike animals 8. List three features that account for the success of arthropods 9. Define and distinguish among the four major arthropod lineages 102