Animals and Animal DiversityThe Nitty-gritty!

Note:

• There is no red on this powerpoint, all non-essentials were deleted from the notes.

• Just imagine that everything is in red!

Basic Characteristics• Multicellular

• Heterotrophic

• Mobile

• Eukaryotic

• Lack cell walls

• Bodies are held together by structural proteins like collagen

• Nervous and muscular tissue unique to animal kingdom

Ch 32?

Reproduction and Development

• Most reproduce sexually, with the diploid stage usually dominating the life cycle

• After a sperm fertilizes an egg, the zygote undergoes rapid cell division called cleavage

• Cleavage leads to formation of a blastula

• The blastula undergoes gastrulation, forming a gastrula with different layers of embryonic tissues

Video: Sea Urchin Embryonic DevelopmentVideo: Sea Urchin Embryonic Development

Fig. 32-2-3

Zygote

Cleavage

Eight-cell stage

Cleavage Blastula

Cross sectionof blastula

Blastocoel

Gastrulation

BlastoporeGastrula

Archenteron

Ectoderm

Endoderm

Blastocoel

• Many animals have at least one larval stage (sexually immature morphology that is different from the adult), which eventually undergoes metamorphosis

• All animals, and only animals, have Hox genes that regulate the development of body form

Paleozoic Era (542–251 Million Years Ago) – The rise of the animal kingdom

• The Cambrian explosion (535 to 525 million years ago) marks the earliest fossil appearance of many major groups of living animals

• There are several hypotheses regarding the cause of the Cambrian explosion– New predator-prey relationships– A rise in atmospheric oxygen– The evolution of the Hox gene complex

Concept 32.3: Animals can be characterized by “body plans”

• Zoologists sometimes categorize animals according to a body plan, a set of morphological and developmental traits

Symmetry

• Animals can be categorized according to the symmetry of their bodies, or lack of it

• Some animals have radial symmetry, while others show bilateral symmetry.

Radial

Bilateral

• Two-sided symmetry is called bilateral symmetry

• Bilaterally symmetrical animals have:– A dorsal (top) side and a ventral (bottom) side– A right and left side– Anterior (head) and posterior (tail) ends– Cephalization, the development of a head

Tissues

• Animal body plans also vary according to the organization of the animal’s tissues

• Tissues are collections of specialized cells isolated from other tissues by membranous layers

• During development, three germ layers give rise to the tissues and organs of the animal embryo

• Ectoderm is the germ layer covering the embryo’s surface

• Endoderm is the innermost germ layer and lines the developing digestive tube, called the archenteron

• Diploblastic animals have ectoderm and endoderm

• Triploblastic animals also have an intervening mesoderm layer; these include all bilaterians

Body Cavities

• Most triploblastic animals possess a body cavity

• A true body cavity is called a coelom and is derived from mesoderm

• Coelomates are animals that possess a true coelom

Fig. 32-8a

CoelomBody covering(from ectoderm)

Digestive tract(from endoderm)

Tissue layerlining coelomand suspendinginternal organs (from mesoderm)

(a) Coelomate

• A pseudocoelom is a body cavity derived from the mesoderm and endoderm

• Triploblastic animals that possess a pseudocoelom are called pseudocoelomates

Fig. 32-8b

Pseudocoelom

Body covering(from ectoderm)

Muscle layer(frommesoderm)

Digestive tract(from endoderm)

(b) Pseudocoelomate

• Triploblastic animals that lack a body cavity are called acoelomates

Fig. 32-8c

(c) Acoelomate

Body covering(from ectoderm)

Wall of digestive cavity(from endoderm)

Tissue-filled region(from mesoderm)

Protostome and Deuterostome Development

• Based on early development, many animals can be categorized as having protostome development or deuterostome development

Cleavage

• In protostome development, cleavage is spiral and determinate

• In deuterostome development, cleavage is radial and indeterminate

• With indeterminate cleavage, each cell in the early stages of cleavage retains the capacity to develop into a complete embryo

• Indeterminate cleavage makes possible identical twins, and embryonic stem cells

Fig. 32-9

Protostome development(examples: molluscs,

annelids)

Deuterostome development(examples: echinoderm,

chordates)

Eight-cell stage Eight-cell stage

Spiral and determinate Radial and indeterminate

Coelom

Archenteron

(a) Cleavage

(b) Coelom formation

Coelom

KeyEctodermMesodermEndoderm

Mesoderm MesodermBlastopore Blastopore

Solid masses of mesodermsplit and form coelom.

Folds of archenteronform coelom.

Anus Mouth

Digestive tube

Mouth AnusMouth develops from blastopore. Anus develops from blastopore.

(c) Fate of the blastopore

Fig. 32-9a

Eight-cell stage Eight-cell stage(a) Cleavage

Spiral and determinate Radial and indeterminate

Protostome development(examples: molluscs,

annelids)

Deuterostome development(examples: echinoderms,

chordates)

Coelom Formation• In protostome development, the splitting of

solid masses of mesoderm forms the coelom• In deuterostome development, the

mesoderm buds from the wall of the archenteron to form the coelom

Fig. 32-9b

Coelom

Protostome development(examples: molluscs,

annelids)

Deuterostome development(examples: echinoderms,

chordates)

(b) Coelom formation

Key

EctodermMesoderm

Endoderm

MesodermMesoderm

Coelom

Archenteron

Blastopore Blastopore

Solid masses of mesodermsplit and form coelom.

Folds of archenteronform coelom.

Fate of the Blastopore

• The blastopore forms during gastrulation and connects the archenteron to the exterior of the gastrula

• In protostome development, the blastopore becomes the mouth

• In deuterostome development, the blastopore becomes the anus

Fig. 32-9c

Anus

Protostome development(examples: molluscs,

annelids)

Deuterostome development(examples: echinoderms,

chordates)

Anus

Mouth

Mouth

Digestive tube

(c) Fate of the blastopore

Key

EctodermMesoderm

Endoderm

Mouth develops from blastopore. Anus develops from blastopore.

Modeling Time

• Let’s go back to the lab.– Take a sheet of paper with you– Pick up a direction sheet– Get 2 colors of dough

InvertebratesThose without backbones – make up about 95%

of animals

Fig. 33-2

ANCESTRALPROTIST

Commonancestor ofall animals

Calcareaand Silicea

Eu

me

tazo

a

Bila

teria

Cnidaria

Lophotrochozoa

Ecdysozoa

Deuterostomia

Sponges

• Lack true tissues and organs• Live in water (both fresh and salt)

• suspension feeders, capturing food particles suspended in the water that pass through their body

• Most sponges are hermaphrodites: Each individual functions as both male and female

Fig. 33-4

Azure vase sponge (Callyspongiaplicifera)

Spongocoel

Osculum

Pore

Epidermis Waterflow

Mesohyl

Choanocyte

Flagellum

Collar

Food particlesin mucus

Choanocyte

AmoebocytePhagocytosis offood particles

Spicules

Amoebocytes

Cnidarians• include jellies, corals, and hydras• exhibit a relatively simple diploblastic, radial body

plan• body plan is a sac with a central digestive

compartment, the gastrovascular cavity• A single opening functions as mouth and anus• There are two variations on the body plan: the

sessile polyp and motile medusa• Carnivores that use tentacles to capture prey

– Armed with enidocytes – cells that fxn in defense and capturing prey

– Nematocysts – organelles that eject a stinging thread

Fig. 33-5

PolypMouth/anus

Bodystalk

Tentacle

Gastrovascularcavity

Gastrodermis

Mesoglea

Epidermis

TentacleMouth/anus

Medusa

Fig. 33-6

Tentacle

Nematocyst

“Trigger”

Cuticleof prey

Threaddischarges

Thread(coiled)

Cnidocyte

Thread

Flatworms

• live in marine, freshwater, and damp terrestrial habitats

• acoelomates • They are flattened dorsoventrally and have a

gastrovascular cavity• Gas exchange takes place across the surface

Fig. 33-10

Pharynx

Gastrovascularcavity

Mouth

Eyespots

Ganglia Ventral nerve cords

Tapeworms

• Tapeworms are parasites of vertebrates and lack a digestive system

• Tapeworms absorb nutrients from the host’s intestine

• Fertilized eggs, produced by sexual reproduction, leave the host’s body in feces

Rotifers

• Rotifers are tiny animals that inhabit fresh water, the ocean, and damp soil

• Rotifers have an alimentary canal, a digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom

• Rotifers reproduce by parthenogenesis, in which females produce offspring from unfertilized eggs

• Some species are unusual in that they lack males entirely

Mollusca• Phylum Mollusca includes snails and slugs,

oysters and clams, and octopuses and squids• Most molluscs are marine• Molluscs are soft-bodied animals, but most

are protected by a hard shell• 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

Fig. 33-15

Nephridium Visceral mass

Coelom

Mantle

Mantlecavity

Heart

Intestine

Gonads

Stomach

Shell

Radula

MouthEsophagusNerve

cordsFoot

Gill

Anus

Mouth

Radula

Gastropods

• Most gastropods are marine,

• Most have a single, spiraled shell

• Slugs lack a shell or have a reduced shell

• The most distinctive characteristic of gastropods is torsion, which causes the animal’s anus and mantle to end up above its head

Fig. 33-17

(a) A land snail

(b) A sea slug

Fig. 33-18

Mouth

Anus

Mantlecavity

Stomach Intestine

Bivalves

• Molluscs of class Bivalvia include many species of clams, oysters, mussels, and scallops

• They have a shell divided into two halves

• The mantle cavity of a bivalve contains gills that are used for feeding as well as gas exchange

Fig. 33-19

Fig. 33-20

Mouth

Digestivegland

MantleHinge area

Gut

Coelom

Heart Adductormuscle

Anus

Excurrentsiphon

Waterflow

IncurrentsiphonGillGonad

Mantlecavity

Foot

Palp

Shell

Cephalopods

• Class Cephalopoda includes squids and octopuses, carnivores with beak-like jaws surrounded by tentacles of their modified foot

• Cephalopods have a closed circulatory system, well-developed sense organs, and a complex brain

Chambered nautilus

Squid

Octopus

Annelids

• Annelids have bodies composed of a series of fused rings

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

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

• Some are parasitic

Arthropods

• The arthropod body plan consists of a segmented body, hard exoskeleton, and jointed appendages,

Fig. 33-29

Cephalothorax

Antennae(sensoryreception) Head

Thorax

Abdomen

Swimming appendages(one pair locatedunder eachabdominal segment)

Walking legs

Mouthparts (feeding)Pincer (defense)

• 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

• Arthropods have an open circulatory system in which fluid called hemolymph is circulated into the spaces surrounding the tissues and organs

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, feeding, and gas exchange

• Males and females are usually separate, and sexual reproduction is external

Fig. 33-39

AnusStomach

Spine

Gills

Madreporite

Radialnerve

Gonads

Ampulla

Podium

Tubefeet

Radial canal

Ringcanal

Central disk

Digestive glands

Fig. 33-40

(a) A sea star (class Asteroidea)

(c) A sea urchin (class Echinoidea)

(e) A sea cucumber (class Holothuroidea)

(b) A brittle star (class Ophiuroidea)

(d) A feather star (class Crinoidea)

(f) A sea daisy (class Concentricycloidea)

Vertebrates

The ones with backbones

Chordata

• Four key characters of chordates:– Notochord– Dorsal, hollow nerve cord– Pharyngeal slits or clefts– Muscular, post-anal tail

Fig. 34-3

Dorsal,hollow

nerve cord

AnusMuscular,

post-anal tail

Pharyngealslits or clefts

Notochord

Mouth

Musclesegments

• The notochord is a longitudinal, flexible rod between the digestive tube and nerve cord

• It provides skeletal support throughout most of the length of a chordate

• In most vertebrates, a more complex, jointed skeleton develops, and the adult retains only remnants of the embryonic notochord

• The nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the notochord

• The nerve cord develops into the central nervous system: the brain and the spinal cord

• In most chordates, grooves in the pharynx called pharyngeal clefts develop into slits that open to the outside of the body

• Functions of pharyngeal slits:– Suspension-feeding structures in many invertebrate chordates

– Gas exchange in vertebrates (except vertebrates with limbs, the tetrapods)

– Develop into parts of the ear, head, and neck in tetrapods

• Chordates have a tail posterior to the anus

• In many species, the tail is greatly reduced during embryonic development

• The tail contains skeletal elements and muscles

• It provides propelling force in many aquatic species

Early Chordate Evolution

• Ancestral chordates may have resembled lancelets

• Gene expression in lancelets holds clues to the evolution of the vertebrate form

Fig. 34-6

BF1

Brain of vertebrate embryo(shown straightened)

HindbrainForebrain Midbrain

Nerve cord of lancelet embryo

BF1

Hox3Otx

Otx Hox3

Concept 34.2: Craniates are chordates that have a head

• The origin of a head opened up a completely new way of feeding for chordates: active predation

• Craniates share some characteristics: a skull, brain, eyes, and other sensory organs

Derived Characters of Craniates

• Craniates have two clusters of Hox genes; lancelets and tunicates have only one cluster

• One feature unique to craniates is the neural crest, a collection of cells near the dorsal margins of the closing neural tube in an embryo

• Neural crest cells give rise to a variety of structures, including some of the bones and cartilage of the skull

Fig. 34-7

Migrating neuralcrest cellsNotochord

Dorsal edgesof neural plate

Neuralcrest

Neuraltube

Derived Characters of Vertebrates

• Vertebrates have the following derived characters:– Vertebrae enclosing a spinal cord– An elaborate skull– Fin rays, in the aquatic forms

Lampreys

• Lampreys (Petromyzontida) represent the oldest living lineage of vertebrates

• They are jawless vertebrates inhabiting various marine and freshwater habitats

• They have cartilaginous segments surrounding the notochord and arching partly over the nerve cord

Chondrichthyans (Sharks, Rays, and Their Relatives)

• Chondrichthyans (Chondrichthyes) have a skeleton composed primarily of cartilage

• The cartilaginous skeleton evolved secondarily from an ancestral mineralized skeleton

• Includes the sharks, rays, and skates

Pelvic fins

Fig. 34-16

Intestine

Adipose fin(characteristicof trout)

Cut edgeof operculum

Swimbladder Caudal

fin

Lateralline

UrinarybladderPelvic

fin

Anus

Dorsal finSpinal cord

Brain

Nostril

Gills

Kidney

Heart

Liver

Gonad

Anal fin

Stomach

Ray-Finned Fishes and Lobe-Fins

Fishes control their buoyancy with an air sac known as a swim bladder

Fig. 34-17

(a) Yellowfin tuna (Thunnus albacares)

(b) Clownfish (Amphiprion ocellaris)

(c) Sea horse (Hippocampus       ramulosus)

(d) Fine-spotted moray eel (Gymnothorax dovii)

Tetrapods

• Tetrapods have some specific adaptations:– Four limbs, and feet with digits– Ears for detecting airborne sounds

Fig. 34-19

Tetrapodlimbskeleton

Bonessupportinggills

Amphibians

• Amphibian means “both ways of life,” referring to the metamorphosis of an aquatic larva into a terrestrial adult

• Most amphibians have moist skin that complements the lungs in gas exchange

• Fertilization is external in most species, and the eggs require a moist environment

Fig. 34-22

(c) Mating adults

(a) Tadpole

(b) During metamorphosis

Concept 34.6: Amniotes are tetrapods that have a terrestrially adapted egg

• Amniotes are a group of tetrapods whose living members are the reptiles, including birds, and mammals

• Have an amniotic egg, which contains membranes that protect the embryo

• Other terrestrial adaptations include relatively impermeable skin and the ability to use the rib cage to ventilate the lungs

Fig. 34-25

Yolk sac

Amnioticcavitywithamnioticfluid

Chorion

Amnion

Albumen

Yolk(nutrients)

Allantois

Embryo

Shell

Reptiles

• Reptiles have scales that create a waterproof barrier

• They lay shelled eggs on land

• Most reptiles are ectothermic, absorbing external heat as the main source of body heat

• Birds are endothermic, capable of keeping the body warm through metabolism

Fig. 34-26

Birds

• Many characters of birds are adaptations that facilitate flight

• The major adaptation is wings with keratin feathers

• Other adaptations include lack of a urinary bladder, females with only one ovary, small gonads, and loss of teeth

Fig. 34-28

(a) Wing

(b) Bone structure

(c) Feather structure

Finger 1

Finger 2

Finger 3

Palm

Hook

VaneBarbuleBarbShaft

WristForearm

Shaft

Fig. 34-29

Airfoil wingwith contourfeathers

Toothed beak Wing claw

Long tail withmany vertebrae

Mammals

• Mammals have– Mammary glands, which produce milk– Hair – A larger brain than other vertebrates of

equivalent size– Differentiated teeth

three living lineages of mammals emerged: monotremes, marsupials,

and eutherians• Monotremes are a small group of egg-laying

mammals consisting of echidnas and the platypus

• Marsupials – when the embryo develops within a placenta in the mother’s uterus

• A marsupial is born very early in its development• It completes its embryonic development while

nursing in a maternal pouch called a marsupium• eutherians have a longer period of pregnancy• Young eutherians complete their embryonic

development within a uterus, joined to the mother by the placenta

Fig. 34-32

Fig. 34-33

(a) A young brushtail possum

(b) Long-nosed bandicoot

Fig. 34-34

Plantigale

Marsupialmammals

Eutherianmammals

Marsupialmammals

Eutherianmammals

Marsupial mole

Flying squirrelSugar glider

Deer mouse

Mole

Tasmanian devil

Wombat

Kangaroo

Woodchuck

Patagonian cavy

Wolverine

Primates

• Most primates have hands and feet adapted for grasping

• Other derived characters of primates: – A large brain and short jaws– Forward-looking eyes close together on the

face, providing depth perception– Complex social behavior and parental care– A fully opposable thumb (in monkeys and

apes)

Fig. 34-36

Fig. 34-38

(a) New World monkey (b) Old World monkey

Humans

• A number of characters distinguish humans from other apes:– Upright posture and bipedal locomotion– Larger brains– Language capabilities and symbolic thought– The manufacture and use of complex tools– Shortened jaw– Shorter digestive tract

Fig. 34-40

Homoerectus

Homohabilis

Homosapiens

Homoneanderthalensis?Homo

ergaster

Paranthropusrobustus

Paranthropusboisei

Australopithecusafricanus

Australopithecusgarhi

Australopithecusafarensis

Sahelanthropustchadensis

Orrorin tugenensis

Ardipithecusramidus

Australo-pithecusanamensis

Kenyanthropusplatyops

HomorudolfensisM

illio

ns

of

year

s ag

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