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Transcript
Chapter 26: Animals – The Invertebrates
General 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
mesoderm
Diversity 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 another
Puzzles 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 parent
Cnidarians – 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 polyp
Comb Jellies
 Radial symmetry
 Weak – swimming predators in plankton communities
 Eight rows of comblike structures made of thick fused cilia
 Do not produce nematocysts
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 – 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 task
Flatworms (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 habitats
Roundworms (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 nutrients
Rotifers (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

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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
brain
Twisting 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 organs
Hiding Out One Way or Another
 A shell is an advantage against predators
 Dig into sand to hide
On 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
siphon
Annelids – 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 setae
Advantages of Segmentation
 Individual parts can undergo modification and become highly adapted for
specific tasks
Annelid 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 surface
Arthropod
 Trilobites (extinct)
 Chelicerates – spiders
 Crustaceans – barnacles and crabs
 Uniramians – centipedes, millipedes, insects
 Arthropod means jointed foot
Adaptations 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 directions
Division 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 reproduction
A








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 tissues
A







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 snails
A









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 Invertebrates
General 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
mesoderm
Diversity 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 another
Puzzles 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 hide
On 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 tasks
Annelid 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 reproduction
A 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 snails
A 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 –