domain bacteria domain archaea domain eukarya common ancestor kingdom: animals domain eukarya

DomainBacteria

DomainArchaea

DomainEukarya

Common ancestor

Kingdom: Animals

Domain Eukarya

Animal Characteristics • Heterotrophs

– must ingest others for nutrients

• Multicellular– complex bodies

• No cell walls– allows active movement

• Sexual reproduction– no alternation of generations– no haploid gametophyte

• The major grades are distinguished by structural changes at four deep branches.

(1) The first branch point splits the Parazoa which lack true tissues from the Eumetazoa which have true tissues.– The parazoans, phylum Porifera or sponges,

represent an early branch of the animal kingdom.

– Sponges have unique development and a structural simplicity.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

(2) The eumetazoans are divided into two major branches, partly based on body symmetry.– Radial symmetry: Phylum Cnidaria (hydras,

jellies, sea anemones and their relatives) and Phylum Ctenophora (comb jellies)

– Bilateria: has bilateral symmetry with a dorsal and ventral side, an anterior and posterior end, and a left and right side.


• Linked with bilateral symmetry is cephalization, (formation of a “head”) concentration of sensory equipment on the anterior end.

• The symmetry of an animal generally fits its lifestyle.– Many radial animals are sessile or planktonic

and need to meet the environment equally well from all sides.

– Animals that move actively are bilateral, such that the head end is usually first to encounter food, danger, and other stimuli.


• The basic organization of germ layers differs between radiata and bilateria.

• Radiata are diploblastic because they have two germ layers. – The ectoderm, covering the surface of the embryo, give

rise to the outer covering and, in some phyla, the central nervous system.

– The endoderm, the innermost layer, lines the developing digestive tube, or archenteron, and gives rise to the lining of the digestive tract and the organs derived from it, such as the liver and lungs of vertebrates.


• The bilateria are triploblastic.– The third germ layer, the mesoderm lies

between the endoderm and ectoderm.– The mesoderm develops into the muscles and

most other organs between the digestive tube and the outer covering of the animal.


(3) The Bilateria can be divided by the presence or absence of a body cavity (a fluid-filled space separating the digestive tract from the outer body wall)

Acoelomates (the phylum Platyhelminthes) have a solid body and lack a body cavity

Pseudocoelom: a body cavity, but it is not completely lined by mesoderm; includes the rotifers (phylum Rotifera) and the roundworms (phylum Nematoda).

Coelomates: are organisms with a true coelom, a fluid-filled body cavity completely lined by mesoderm.

The inner and outer layers of tissue that surround the cavity connect dorsally and ventrally to form mesenteries, which suspend the internal organs.


Porifera

Cnidaria

Platyhelminthes

sponges jellyfish flatworms roundworms

Nematoda

Mollusca Arthropoda Chordata

Annelida Echinodermata

mollusks

multicellularity

Ancestral Protist

tissues

bilateral symmetry

body cavity

segmentation

Animal Evolution

coelom

starfish vertebrates

endoskeleton

segmentedworms

insectsspiders

backbone

specialization & body complexity

specialized structure & function,muscle & nerve tissue

distinct body plan; cephalization

body complexity digestive & repro sys

digestive sys

body size

redundancy,specialization, mobility

body & brain size, mobility

radial

bilateral

Body Cavityectoderm

ectoderm

mesodermendoderm

ectodermmesoderm

endoderm

mesodermendoderm

acoelomate

pseudocoelomate

coelomate

coelom cavity

pseudocoel

• Space for organ system development– increase digestive &

reproductive systems• increase food

capacity & digestion• increase gamete

production

• Coelem– mesoderm &

endoderm interact during development

– allows complex structures to develop in digestive system• ex. stomach

protostome vs. deuterostome

(4) The coelomate phyla are divided into two grades based on differences in their development.– The mollusks, annelids, arthropods, and

several other phyla belong to the protostomes, while echinoderms, chordates, and some other phyla belong to the deuterostomes.

– These differences center on cleavage pattern, coelom formation, and blastopore fate.



Fig. 32.7

Blastual: Hollow Ball

Gastrula

Blue-Ectoderm

Red-Mesoderm

Yellow-Endoderm

• The fossil record and molecular studies concur that the diversification that produced most animal phyla occurred rapidly on the vast scale of geologic time.

• This lasted about 40 million years (about 565 to 525 million years ago) during the late Precambrian and early Cambrian (which began about 543 million years ago).

Most animal phyla originated in a relatively brief span of geologic time


• Nearly all the major animal body plans appear in Cambrian rocks from 543 to 525 million years ago.

• During this relatively short time, a burst of animal origins, the Cambrian explosion, left a rich fossil assemblage.– It includes the first animals with hard,

mineralized skeletons


Invertebrate: Platyhelminthes

ectoderm

mesoderm

endoderm

• Flatworms– tapeworm, planaria– mostly parasitic– bilaterally symmetrical

• have right & left & then have head (anterior) end & posterior end – cephalization = development of brain– concentration of sense organs in head

• increase specialization in body plan

acoelomate

• Flatworms are divided into four classes: Turbellaria, Monogenia, Trematoda, and Cestoidea.

• Planarians and other flatworms lack organs specialized for gas exchange and circulation.– Their flat shape places all cells close to the

surrounding water and fine branching of the digestive system distributes food throughout the animal.

– Nitrogenous wastes are removed by diffusion and simple ciliated flame cells help maintain osmotic balance.

Fig. 33.10

Invertebrate: Nematoda

• Roundworms– bilaterally symmetrical– body cavity

• pseudocoelom = simple body cavity• digestive system

– tube running through length of body (mouth to anus)

– many are parasitic• hookworm

C. elegans

Invertebrate: Mollusca• Mollusks

– slugs, snails, clams, squid– bilaterally symmetrical (with exceptions)

– soft bodies, mostly protected by hard shells– true coelem

• increases complexity & specialization of internal organs

• Despite their apparent differences, all mollusks have a similar body plan with a muscular foot (typically for locomotion), a visceral mass with most of the internal organs, and a mantle.– The mantle, which secretes the shell, drapes

over the visceral mass and creates a water-filled chamber, the mantle cavity, with the gills, anus, and excretory pores.

– Many mollusks feed by using a straplike rasping organ, a radula, to scrape up food.

• The basic molluscan body plan has evolved in various ways in the eight classes of the phylum.– The four most

prominent are the Polyplacophora (chitons), Gastropoda (snails and slugs), Bivalvia (clams, oysters, and other bivalves), and Cephalopoda (squids, octopuses, and nautiluses).

Invertebrate: Annelida• Segmented worms

– earthworms, leeches– segments

• increase mobility• redundancy in body sections

– bilaterally symmetrical– true coelem fan worm leech

Polychete Worm

• The coelom of the earthworm, a typical annelid, is partitioned by septa, but the digestive tract, longitudinal blood vessels, and nerve cords penetrate the septa and run the animal’s length.


Fig. 33.23

• The phylum Annelida is divided into three classes: Oligochaeta, Polychaeta, and Hirudinea.


Invertebrate: Arthropoda

• Spiders, insects, crustaceans– most successful animal phylum– bilaterally symmetrical– segmented

• specialized segments• allows jointed appendages

– exoskeleton• chitin + protein

• Metamorphosis: improtant in insects• In incomplete metamorphosis (seen in

grasshoppers and some other orders), the young resemble – Through a series of molts, the young look more and more like

adults until it reaches full size.

• In complete metamorphosis, larval stages specialized for eating and growing change morphology completely during the pupal stage and emerge as adults.


Fig. 33.34

Arthropod groups

insects6 legs, 3 body parts

crustaceansgills, 2 pairs antennaecrab, lobster, barnacles, shrmp

arachnids8 legs, 2 body partsspiders, ticks, scorpions

Invertebrate: Echinodermata

• Starfish, sea urchins, sea cucumber– radially symmetrical as adults– spiny endoskeleton– deuterostome

loss of bilateral symmetry?

Invertebrate quick check…

• Which group includes snails, clams, and squid?• Which group is the sponges?• Which are the flatworms?

…segmented worms?…roundworms?

• Which group has jointed appendages & an exoskeleton?

• Which two groups have radial symmetry?• What is the adaptive advantage of bilateral

symmetry?• Which group has no symmetry?

Invertebrates: Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata

• Vertebrates– fish, amphibians, reptiles, birds, mammals– internal bony skeleton

• backbone encasing spinal column

• skull-encased brain

– deuterostome

postanaltail notochord

hollow dorsalnerve cord

pharyngealpouches

Chordata

becomes brain & spinal cord

becomes vertebrae

becomes gills or Eustachian tube

becomes tail or tailbone

Vertebrates: Fish salmon, trout, sharks

450 mya450 mya

• Characteristics – body structure

• bony & cartilaginous skeleton• jaws & paired appendages (fins)• scales

– body function• gills for gas exchange• two-chambered heart;

single loop blood circulation• ectotherms

– reproduction• external fertilization• external development in

aquatic egg

gills

body

Transition to LandEvolution of tetrapods

Tibia

Femur

Fibula

Humerus Shoulder

RadiusUlna

Tibia

FemurPelvis

Fibula Lobe-finned fish

Humerus

Shoulder

Radius

Ulna

Pelvis

Early amphibian

lung

buccalcavity

glottisclosed

Vertebrates: Amphibian• Characteristics

– body structure• legs (tetrapods)• moist skin

– body function• lungs (positive pressure) &

diffusion through skin for gas exchange• three-chambered heart;

veins from lungs back to heart• ectotherms

– reproduction• external fertilization• external development in aquatic egg• metamorphosis (tadpole to adult)

frogssalamanders toads

350 mya350 mya

Vertebrates: Reptiles• Characteristics

– body structure• dry skin, scales, armor

– body function• lungs for gas exchange• thoracic breathing; negative pressure• most have three-chambered heart• ectotherms

– reproduction• internal fertilization• external development in

amniotic egg

250 mya250 mya

dinosaurs, turtles lizards, snakesalligators, crocodile

embryoleatheryshell

chorion

allantoisyolk sac

amnion

Vertebrates: Birds (Aves)• Characteristics

– body structure• feathers & wings• thin, hollow bone;

flight skeleton

– body function• very efficient lungs & air sacs• four-chambered heart• endotherms

– reproduction• internal fertilization• external development in

amniotic egg

150 mya150 mya

finches, hawk ostrich, turkey

trachea

anteriorair sacs

lung

posteriorair sacs

Vertebrates: Mammals220 mya / 65 mya220 mya / 65 mya

mice, ferret elephants, batswhales, humans

musclescontract

diaphragmcontracts

• Characteristics – body structure

• hair• specialized teeth

– body function• lungs, diaphragm; negative pressure• four-chambered heart• endotherms

– reproduction• internal fertilization• internal development in uterus

– nourishment through placenta

• birth live young• mammary glands make milk

Vertebrates: Mammals• Sub-groups

– monotremes• egg-laying mammals• lack placenta & true nipples• duckbilled platypus, echidna

– marsupials• pouched mammals

– offspring feed from nipples in pouch

• short-lived placenta• koala, kangaroo, opossum

– placental• true placenta

– nutrient & waste filter

• shrews, bats, whales, humans

That’s the buzz!

AnyQuestions?

domain bacteria domain archaea domain eukarya common ancestor kingdom: animals domain eukarya

Documents

body symmetry

pearson education

bilateral symmetry

solid body

benjamin cummingsthe

body cavitypseudocoelom

phylum platyhelminthes

phylum porifera