Download presentation
Presentation is loading. Please wait.
1
An Introduction to Invertebrates
Chapter 33 An Introduction to Invertebrates
2
Overview: Life Without a Backbone
Invertebrates are animals that lack a backbone They account for 95% of known animal species They are morphologically diverse For example, the Christmas tree worm (Spirobranchus giganteus) has tentacles for gas exchange and feeding © 2011 Pearson Education, Inc.
3
Figure 33.1 Figure 33.1 What function do the red whorls of this organism have?
4
Porifera ANCESTRAL PROTIST Cnidaria Eumetazoa Common Lophotrochozoa
Figure 33.2 Porifera ANCESTRAL PROTIST Cnidaria Common ancestor of all animals Lophotrochozoa Eumetazoa Ecdysozoa Bilateria Figure 33.2 Review of animal phylogeny. Deuterostomia
5
Concept 33.1: Sponges are basal animals that lack true tissues
Animals in the phylum Porifera are known informally as sponges They are sedentary and live in marine waters or fresh water © 2011 Pearson Education, Inc.
6
Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
Figure 33.UN01 Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia Figure 33.UN01 In-text figure, p. 670
7
Sponges lack true tissues and organs
Sponges are suspension feeders, capturing food particles suspended in the water that passes through their body Water is drawn through pores into a cavity called the spongocoel and out through an opening called the osculum Sponges lack true tissues and organs © 2011 Pearson Education, Inc.
8
Food particles in mucus Flagellum Choanocyte Collar Azure vase sponge
Figure 33.4 Food particles in mucus Flagellum Choanocyte Collar Azure vase sponge (Callyspongia plicifera) Choanocyte Osculum Spongocoel Phagocytosis of food particles Amoebocyte Pore Figure 33.4 Anatomy of a sponge. Spicules Epidermis Water flow Amoebocytes Mesohyl
9
Choanocytes, flagellated collar cells, generate a water current through the sponge and ingest suspended food Sponges consist of a gelatinous noncellular mesohyl layer between two cell layers Amoebocytes are found in the mesohyl and play roles in digestion and structure Most sponges are hermaphrodites: Each individual functions as both male and female © 2011 Pearson Education, Inc.
10
Concept 33.2: Cnidarians are an ancient phylum of eumetazoans
All animals except sponges and a few other groups belong to the clade Eumetazoa, animals with true tissues Phylum Cnidaria is one of the oldest groups in this clade © 2011 Pearson Education, Inc.
11
Porifera Cnidaria Eumetazoa Lophotrochozoa Ecdysozoa Deuterostomia
Figure 33.UN02 Porifera Cnidaria Lophotrochozoa Eumetazoa Ecdysozoa Deuterostomia Figure 33.UN02 In-text figure, p. 671
12
They exhibit a relatively simple diploblastic, radial body plan
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 The basic body plan of a cnidarian is a sac with a central digestive compartment, the gastrovascular cavity A single opening functions as mouth and anus © 2011 Pearson Education, Inc.
13
A polyp adheres to the substrate by the aboral end of its body
There are two variations on the body plan: the sessile polyp and motile medusa A polyp adheres to the substrate by the aboral end of its body A medusa has a bell-shaped body with its mouth on the underside Medusae do not attach to the substate but move freely © 2011 Pearson Education, Inc.
14
Mouth/anus Tentacle Gastrovascular cavity Gastrodermis Mesoglea Body
Figure 33.5 Mouth/anus Tentacle Gastrovascular cavity Gastrodermis Mesoglea Body stalk Epidermis Figure 33.5 Polyp and medusa forms of cnidarians. Tentacle Mouth/anus Polyp Medusa
15
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 © 2011 Pearson Education, Inc.
16
Tentacle Cuticle of prey Thread Nematocyst “Trigger” Thread discharges
Figure 33.6 Tentacle Cuticle of prey Thread Nematocyst “Trigger” Figure 33.6 A cnidocyte of a hydra. Thread discharges Thread (coiled) Cnidocyte
17
Phylum Cnidaria is divided into four major classes
Hydrozoa Scyphozoa Cubozoa Anthozoa © 2011 Pearson Education, Inc.
18
(b) Scyphozoa (c) Cubozoa (d) Anthozoa (a) Hydrozoa Figure 33.7
Figure 33.7 Cnidarians. (a) Hydrozoa
19
Concept 33.3: Lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms Bilaterian animals have bilateral symmetry and triploblastic development Most have a coelom and a digestive tract with two openings The clade Bilateria contains Lophotrochozoa, Ecdysozoa, and Deuterostomia © 2011 Pearson Education, Inc.
20
Porifera Cnidaria Lophotrochozoa Bilateria Ecdysozoa Deuterostomia
Figure 33.UN03 Porifera Cnidaria Lophotrochozoa Ecdysozoa Bilateria Deuterostomia Figure 33.UN03 In-text figure, p. 674
21
The clade Lophotrochozoa was identified by molecular data
Some develop a lophophore for feeding, others pass through a trochophore larval stage, and a few have neither feature Lophotrochozoa includes the flatworms, rotifers, ectoprocts, brachiopods, molluscs, and annelids © 2011 Pearson Education, Inc.
22
Flatworms Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats Although flatworms undergo triploblastic development, they are acoelomates They are flattened dorsoventrally and have a gastrovascular cavity with one opening Gas exchange takes place across the surface, and protonephridia regulate the osmotic balance © 2011 Pearson Education, Inc.
23
Flatworms are divided into two lineages
Catenulida, or “chain worms,” reproduce asexually by budding Rhabditophora are more diverse and include both free-living and parasitic species © 2011 Pearson Education, Inc.
24
Figure 33.9 Figure 33.9 A free-living marine flatworm. 5 mm
25
Free-Living Species The best-known rhabditophorans are planarians
Planarians live in fresh water and prey on smaller animals Planarians have light-sensitive eyespots and centralized nerve nets © 2011 Pearson Education, Inc.
26
The planarian nervous system is more complex and centralized than the nerve nets of cnidarians
Planarians are hermaphrodites and can reproduce sexually, or asexually through fission © 2011 Pearson Education, Inc.
27
Gastrovascular cavity Pharynx
Figure 33.10 Gastrovascular cavity Pharynx Gastrovascular cavity Mouth Eyespots Figure Anatomy of a planarian. Ventral nerve cords Ganglia
28
Parasitic Species Parasitic rhabditophorans live in or on other animals Two important groups of parasitic rhabditophorans are the trematodes and the tapeworms © 2011 Pearson Education, Inc.
29
Trematodes Trematodes parasitize a wide range of hosts, and most have complex life cycles with alternating sexual and asexual stages Trematodes that parasitize humans spend part of their lives in snail hosts They produce surface proteins that mimic their host and release molecules that manipulate the host’s immune system © 2011 Pearson Education, Inc.
30
Male Human host Female 1 mm Mature flukes Motile Ciliated larva larva
Figure 33.11 Male Human host Female 1 mm Mature flukes Figure The life cycle of a blood fluke (Schistosoma mansoni), a trematode. Motile larva Ciliated larva Snail host
31
Tapeworms Tapeworms are parasites of vertebrates and lack a digestive system Tapeworms absorb nutrients from the host’s intestine © 2011 Pearson Education, Inc.
32
The scolex contains suckers and hooks for attaching to the host
Proglottids are units that contain sex organs and form a ribbon behind the scolex Fertilized eggs, produced by sexual reproduction, leave the host’s body in feces © 2011 Pearson Education, Inc.
33
100 m Hooks Sucker Proglottids with reproductive structures Scolex
Figure 33.12 100 m Hooks Sucker Proglottids with reproductive structures Figure Anatomy of a tapeworm. Scolex
34
Molluscs Phylum Mollusca includes snails and slugs, oysters and clams, and octopuses and squids Most molluscs are marine, though some inhabit fresh water and some snails and slugs are terrestrial Molluscs are soft-bodied animals, but most are protected by a hard shell © 2011 Pearson Education, Inc.
35
All molluscs have a similar body plan with three main parts
Muscular foot Visceral mass Mantle Many molluscs also have a water-filled mantle cavity and feed using a rasplike radula © 2011 Pearson Education, Inc.
36
Nephridium Heart Heart Visceral mass Digestive tract Coelom Intestine
Figure 33.15 Nephridium Heart Heart Visceral mass Digestive tract Coelom Intestine Gonads Mantle Stomach Mantle cavity Shell Mouth Radula Anus Gill Figure The basic body plan of a mollusc. Radula Mouth Nerve cords Foot Esophagus
37
Most molluscs have separate sexes with gonads located in the visceral mass, but many snails are hermaphrodites The life cycle of many molluscs includes a ciliated larval stage called a trochophore © 2011 Pearson Education, Inc.
38
Four of the major classes of molluscs are
Polyplacophora (chitons) Gastropoda (snails and slugs) Bivalvia (clams, oysters, and other bivalves) Cephalopoda (squids, octopuses, cuttlefish, and chambered nautiluses) © 2011 Pearson Education, Inc.
39
Mantle cavity Stomach Intestine Anus Mouth Figure 33.18
Figure The results of torsion in a gastropod.
40
Bivalves Bivalves are marine and include many species of clams, oysters, mussels, and scallops They have a shell divided into two halves drawn together by adductor muscles Some bivalves have eyes and sensory tentacles along the edge of their mantle © 2011 Pearson Education, Inc.
41
Figure 33.19 Figure A bivalve.
42
The mantle cavity of a bivalve contains gills that are used for feeding as well as gas exchange
© 2011 Pearson Education, Inc.
43
Coelom Hinge area Mantle Gut Heart Adductor muscle (one or two)
Figure 33.20 Coelom Hinge area Mantle Gut Heart Adductor muscle (one or two) Digestive gland Anus Mouth Excurrent siphon Figure Anatomy of a clam. Shell Palp Water flow Foot Mantle cavity Incurrent siphon Gonad Gill
44
Cephalopods Cephalopods are carnivores with beak-like jaws surrounded by tentacles of their modified foot Most octopuses creep along the sea floor in search of prey © 2011 Pearson Education, Inc.
45
Squid Octopus Chambered nautilus Figure 33.21
Figure Cephalopods. Chambered nautilus
46
Protecting Freshwater and Terrestrial Molluscs
Molluscs are the animal group with the largest number of recent extinctions The most threatened groups are Freshwater bivalves, including pearl mussels Terrestrial gastropods, including Pacific island land snails These molluscs are threatened by habitat loss, pollution, and non-native species © 2011 Pearson Education, Inc.
47
Recorded extinctions of animal species (Data: International Union for
Figure 33.22 Molluscs Other invertebrates Amphibians Insects Birds Fishes Mammals Reptiles (excluding birds) An endangered Pacific island land snail, Partula suturalis Recorded extinctions of animal species (Data: International Union for Conservation of Nature, 2008) Figure Impact: Molluscs: The Silent Extinction Workers on a mound of pearl mussels killed to make buttons (ca. 1919)
48
Earthworms Earthworms eat through soil, extracting nutrients as the soil moves through the alimentary canal Earthworms are hermaphrodites but cross-fertilize Some reproduce asexually by fragmentation © 2011 Pearson Education, Inc.
49
Giant Australian earthworm
Figure 33.24 Cuticle Coelom Epidermis Septum (partition between segments) Circular muscle Metanephridium Longitudinal muscle Anus Dorsal vessel Chaetae Intestine Skin Ventral vessel Fused nerve cords Nephrostome Metanephridium Clitellum Figure Anatomy of an earthworm, an oligochaete. Esophagus Crop Pharynx Intestine Giant Australian earthworm Cerebral ganglia Gizzard Ventral nerve cords with segmental ganglia Mouth Subpharyngeal ganglion Circulatory system vessels
50
Leeches Most species of leeches live in fresh water; some are marine or terrestrial Leeches include predators of invertebrates, and parasites that suck blood Leeches secrete a chemical called hirudin to prevent blood from coagulating © 2011 Pearson Education, Inc.
51
Figure 33.25 Figure A leech.
52
Concept 33.4: Ecdysozoans are the most species-rich animal group
Ecdysozoans are covered by a tough coat called a cuticle The cuticle is shed or molted through a process called ecdysis The two largest phyla are nematodes and arthropods © 2011 Pearson Education, Inc.
53
Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
Figure 33.UN04 Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia Figure 33.UN04 In-text figure, p. 683
54
Nematodes Nematodes, or roundworms, are 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 © 2011 Pearson Education, Inc.
55
Arthropods 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 © 2011 Pearson Education, Inc.
56
Arthropod Origins The arthropod body plan consists of a segmented body, hard exoskeleton, and jointed appendages This body plan dates to the Cambrian explosion (535–525 million years ago) Early arthropods show little variation from segment to segment © 2011 Pearson Education, Inc.
57
Figure 33.28 Figure A trilobite fossil.
58
Arthropod evolution is characterized by a decrease in the number of segments and an increase in appendage specialization These changes may have been caused by changes in Hox gene sequence or regulation © 2011 Pearson Education, Inc.
59
EXPERIMENT Other ecdysozoans Origin of Ubx and abd-A Hox genes?
Figure 33.29 EXPERIMENT Other ecdysozoans Origin of Ubx and abd-A Hox genes? Arthropods Onychophorans Common ancestor RESULTS Figure Inquiry: Did the arthropod body plan result from new Hox genes? Ant antenna J jaws L1–L15 body segments
60
General Characteristics of Arthropods
The appendages of some living arthropods are modified for functions such as walking, feeding, sensory reception, reproduction, and defense © 2011 Pearson Education, Inc.
61
Pincer (defense) Mouthparts (feeding)
Figure 33.30 Cephalothorax Abdomen Thorax Antennae (sensory reception) Head Swimming appen- dages (one pair per abdominal segment Figure External anatomy of an arthropod. Walking legs Pincer (defense) Mouthparts (feeding)
62
When an arthropod grows, it molts its exoskeleton
The body of an arthropod is completely covered by the cuticle, an exoskeleton made of layers of protein and the polysaccharide chitin When an arthropod grows, it molts its exoskeleton © 2011 Pearson Education, Inc.
63
Arthropods have eyes, olfactory receptors, and antennae that function in touch and smell
Arthropods have an open circulatory system in which hemolymph is circulated into the spaces surrounding the tissues and organs A variety of organs specialized for gas exchange have evolved in arthropods © 2011 Pearson Education, Inc.
64
Molecular evidence suggests that living arthropods consist of four major lineages that diverged early in the phylum’s evolution Chelicerates (sea spiders, horseshoe crabs, scorpions, ticks, mites, and spiders) Myriapods (centipedes and millipedes) Hexapods (insects and relatives) Crustaceans (crabs, lobsters, shrimps, barnacles, and many others) © 2011 Pearson Education, Inc.
65
Scorpion Dust mite Web-building spider 50 m Figure 33.32
Figure Arachnids. Web-building spider
66
Gas exchange in spiders occurs in respiratory organs called book lungs
Arachnids have an abdomen and a cephalothorax, which has six pairs of appendages: the chelicerae, the pedipalps, and four pairs of walking legs Gas exchange in spiders occurs in respiratory organs called book lungs Many spiders produce silk, a liquid protein, from specialized abdominal glands © 2011 Pearson Education, Inc.
67
Stomach Intestine Heart Brain Digestive gland Eyes Ovary Poison gland
Figure 33.33 Stomach Intestine Heart Brain Digestive gland Eyes Ovary Poison gland Figure Anatomy of a spider. Anus Book lung Spinnerets Gonopore (exit for eggs) Chelicera Pedipalp Sperm receptacle Silk gland
68
Myriapods Myriapods are terrestrial, and have jaw-like mandibles
Subphylum Myriapoda includes millipedes and centipedes Myriapods are terrestrial, and have jaw-like mandibles Millipedes eat decaying leaves and plant matter Millipedes have many legs, with two pairs per trunk segment © 2011 Pearson Education, Inc.
69
Figure 33.34 (a) Millipede Figure Myriapods. (b) Centipede
70
Centipedes are carnivores
Centipedes have one pair of legs per trunk segment © 2011 Pearson Education, Inc.
71
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 © 2011 Pearson Education, Inc.
72
Abdomen Thorax Head Compound eye Antennae Heart Dorsal artery Crop
Figure 33.35 Abdomen Thorax Head Compound eye Antennae Heart Dorsal artery Crop Cerebral ganglion Anus Vagina Figure Anatomy of a grasshopper, an insect. Malpighian tubules Ovary Tracheal tubes Nerve cords Mouthparts
73
Insects diversified several times following the evolution of flight, adaptation to feeding on gymnosperms, and the expansion of angiosperms Insect and plant diversity declined during the Cretaceous extinction, but has been increasing in the 65 million years since © 2011 Pearson Education, Inc.
74
Flight is one key to the great success of insects
An animal that can fly can escape predators, find food, and disperse to new habitats much faster than organisms that can only crawl © 2011 Pearson Education, Inc.
75
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 © 2011 Pearson Education, Inc.
76
The larval stage looks entirely different from the adult stage
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 © 2011 Pearson Education, Inc.
77
(a) Larva (caterpillar) (b) Pupa (c) Later-stage pupa (d) Emerging
Figure 33.37 (a) Larva (caterpillar) (b) Pupa (c) Later-stage pupa Figure Complete metamorphosis of a butterfly. (d) Emerging adult (e) Adult
78
Most insects have separate males and females and reproduce sexually
Individuals find and recognize members of their own species by bright colors, sound, or odors Some insects are beneficial as pollinators, while others are harmful as carriers of diseases, or pests of crops Insects are classified into more than 30 orders © 2011 Pearson Education, Inc.
79
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 Small crustaceans exchange gases through the cuticle; larger crustaceans have gills © 2011 Pearson Education, Inc.
80
Most crustaceans have separate males and females
Isopods include terrestrial, freshwater, and marine species Pill bugs are a well known group of terrestrial isopods Decapods are all relatively large crustaceans and include lobsters, crabs, crayfish, and shrimp © 2011 Pearson Education, Inc.
81
(a) Ghost crab (b) Krill (c) Barnacles Figure 33.39
Figure Crustaceans. (b) Krill (c) Barnacles
82
Concept 33.5: Echinoderms and chordates are deuterostomes
Echinoderms (phylum Echinodermata) include sea stars and sea urchins Chordates (phylum Chordata) include the vertebrates Echinoderms and chordates constitute the clade Deuterostomia © 2011 Pearson Education, Inc.
83
Deuterostomes share developmental characteristics
Radial cleavage Formation of the anus from the blastopore However, some other animals also share these developmental characteristics Deuterostomes are defined primarily by DNA similarities © 2011 Pearson Education, Inc.
84
Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
Figure 33.UN05 Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia Figure 33.UN05 In-text figure, p. 692
85
Echinoderms 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 and feeding Males and females are usually separate, and sexual reproduction is external © 2011 Pearson Education, Inc.
86
Short digestive tract Stomach Anus Spine Gills Central disk
Figure 33.40 Short digestive tract Stomach Anus Spine Gills Central disk Madreporite Figure Anatomy of a sea star, an echinoderm. Radial nerve Digestive glands Ring canal Gonads Ampulla Podium Tube feet Radial canal
87
Most adult echinoderms have radial symmetry with multiples of five
Echinoderm larvae have bilateral symmetry © 2011 Pearson Education, Inc.
88
Living echinoderms are divided into five classes
Asteroidea (sea stars and sea daisies) Ophiuroidea (brittle stars) Echinoidea (sea urchins and sand dollars) Crinoidea (sea lilies and feather stars) Holothuroidea (sea cucumbers) © 2011 Pearson Education, Inc.
89
Chordates Phylum Chordata consists of two subphyla of invertebrates as well as hagfishes and vertebrates Chordates are bilaterally symmetrical coelomates with segmented bodies Chordates share many features of embryonic development with echinoderms, but have evolved separately for at least 500 million years © 2011 Pearson Education, Inc. © 2011 Pearson Education, Inc.
Similar presentations
