evolution of animals

sinh học tìm hiểu về sự tiến hóa của động vật từ những năm trước công nguyên cho đến hiện tại, the evolution of animal, animal diversity. Tìm hiểu về sự phát triển của đọng vật

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Lectures by Chris C Romero, updated by Edward J Zalisko

Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey

The Evolution of Animals

Chapter 17

Kingdom: Animalia

 Eukaryotic, multicellular, diploid

 Heterotrophic: Digestion:internal = ingestion

 No cell wall

 Most have muscle, nerve cells - movement (one exception?)

 Developmental stage – embryo

List the characteristics of the kingdom: Animalia?

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ORIGINS OF ANIMAL DIVERSITY

 Precambrian seas (~600–700 million years ago) :

 Evolution from colonial flagellated protist (similar to

choanoflagellate)

 Cambrian period (542 million years ago): rapid diversification

• span of about 15 million years:

– All animal body plans evolved

– Many bizarre

Qns?

choanoflagellate

Animal Phylogeny: 1st trend in Animal Evolution

 1st trend in animal evolution: tissue development :

 sponges lack true tissue

 All other animal groups have tissue development

What is the 1st trend in animal symmetry?

What group of animals do not show tissue development?

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 2 nd evolutionary trend: body symmetry

 Asymmetery: none ex sponges

 Radial symmetry: identical around a central axis (ex.anemone)

 Bilateral symmetry: only one way to split animal into equal halves (most animal groups).

Animal Phylogeny: 2nd Trend in Animal Evolution

Radial symmetry: parts radiate from

center, so any section through central axis

divides into many mirror images

(multiple planes of symmetry)

Bilateral symmetry: only one section can

divide left and right sides into just 2

Explain giving examples

 3 rd evolutionary trend: body cavity

 fluid-filled space separating digestive tract from outer body wall

 body cavity forms:

 1 pseudocoelom : body cavity is not completely lined by mesoderm, (outer mesoderm, inner endoderm) ex round worms

 2 true coelom: completely lined by mesoderm (most animal groups)

 3 Acoelomate: no coelom (ex flatworms)

• www.ucmp.berkeley.edu/cambrian/camb.html

Body Cavity in Animals

(a) No body cavity

(b) Pseudocoelom

(c) True coelom

Body covering (from ectoderm)

Tissue-filled region (from mesoderm)

Body covering (from ectoderm)

Body covering (from ectoderm)

Muscle layer (from mesoderm)

Tissue layer lining coelom and

suspending internal organs (from mesoderm)

Digestive tract (from endoderm)

Digestive tract (from endoderm)

Digestive tract (from endoderm)

4the trend in animal evoluton:

Embryo development

 1 Protostome : blastopore becomes mouth

Ex most invertebrates (roundworms, segmented

worms, arthropods, molluscs)

 2 Deuterostome: blastopore becomes anus

Ex starfish, chordates (fish, amphibians, reptiles,

birds, mammals)

Digestive cavity

What is the difference between protostome &

Ancestral protist

1 Sponges

 Sponges represent multiple phyla.

 attached, do not move

 lack true tissues

 body - sac with pores.

Water flow

Central cavity

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Phylum: 2 Cnidaria

 body tissues ( 2 or 3 layers : ectoderm, endoderm, mesoderm)

 Tentacles with stinging cells (cnidocytes)

 sac with gastrovascular cavity - digestive compartment with

one opening

 carnivores - tentacles, with cnidocytes - capture prey

 body plans:

1 sessile polyp ex anemone

2 floating medusa ex jelly fish

List the characteristics of the phylum Cnidaria (anemones and jelly fish).

How is the polyp body form different from the medusa form? Give examples.

Tentacle

Polyp form

Gastrovascular cavity

Sea anemone

cavity

Mouth/anus

Tentacle Medusa form

Jelly

Figure 17.9b

Coiled thread

How do anemones and jelly fish capture their prey?

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Phylum: 3 Platyhelminthes (Flatworms)

 Simplest, bilateral symmetry.

 include:

 Parasites ex tapeworm

 Free-living ex planaria

 gastrovascular cavity – incomplete gut , one opening

 highly branched gut – increases surface area –

nutrient absorption

 Acoelomate

List the characteristics of flatworms

Do flatworms have an incomplete or complete gut? Explain.

Digestive tract

(gastrovascular

cavity) Nerve cords

Mouth Eyespots (detect light)

Nervous tissue clusters

(simple brain) Planarian Bilateral symmetry

Blood fluke

Suckers

Reproductive unit with skin removed

Tapeworm

How are tapeworms adapted for life

as an endoparasite?

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Phylum: 4 Nematoda (Roundworms)

 Cylindrical, tapered body

 Pseudocoelom

- One-way movement of food

 decomposers – free living

parasites in plants, humans, other animals

Video: C elegans Embryo Development (time lapse)

Video: C elegans Crawling

Phylum: 5 Mollusca

 soft-bodied, protected by shell (some lost shell)

 file-like radula - scrape food

 Coelom

 Complete digestive tract

 body:

 foot - movement

 visceral mass - has internal organs

 Mantle - secretes shell

List the characteristics of the molluscs

speed and agility

Visceral mass

Reproductive organs

Digestive tract

Mantle

cavity

Nerve cords

Digestive tract

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Diversity in Molluscs

Gastropods Bivalves

(hinged shell)

Cephalopods (large brain and tentacles)

Snail (spiraled shell)

Sea slug (no shell)

MAJOR GROUPS OF MOLLUSCS

 2 nd most diverse

 Gastropods: single, spiral shell (some lost shell ex _ )

 Bivalves: shell divided into two, hinged

 Cephalopods: no external shell , some have internal shell

ex. _

some have lost the internal shell ex (agile, speed)

Describe how diversity in molluscs is seen when

 Body segmentation: division of body into series of repeated parts

How do annelids differ from roundworms?

How is a leech adapted for life as an ectoparasite?

Main heart

Digestive tract

Segment walls

Figure 17.15

Earthworms Polychaetes Leeches

MAJOR GROUPS OF ANNELIDS

Christmas tree worm

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Phylum: 7 Arthropoda

 jointed appendages (limbs)

 ~one million species, mostly insects (most diverse) nearly all habitats

 segmented , with appendages for different functions

- feeding, movement, respiration, reproduction

 exoskeleton (made partly of chitin):

 Protection

 Muscle attachment - move appendages

General Characteristics of Arthropods

List the characteristics of the arthropods

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 land

 four pairs of legs- walking, specialized pair - feeding appendages

 spiders, scorpions, ticks, and mites

Arachnids

How can you identify an arachnids and an insect?

 aquatic

 Have multiple pairs of appendages

 crabs, lobsters, crayfish, shrimps, and barnacles

Crustaceans

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 segments - body

 Millipedes:

 decaying plant matter

 two pairs of legs per body segment

 Centipedes:

 carnivores with poison claws

 one pair per body segment

– Have one pair of short legs per body segment

Millipedes and Centipedes

How can you identify a millipede from a centipede?

pair of sensory antennae, pair of eyes

Insect Characteristics

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 Insects outnumber all other forms of life

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Phylum: 8 Echinodermata

 Lack body segments

 radial symmetry as adults but bilateral symmetry as larvae

 endoskeleton

 water vascular system - movement and gas exchange

List the characteristics of echinoderms

Phylum: 9 Chordata

 4 key features in embryo and sometimes adult:

 dorsal, hollow nerve cord

Muscle segments

Notochord

Dorsal, hollow nerve cord

Pharyngeal slits

Brain

Mouth Anus

Post-anal

tail

Figure 17.27

 3 groups of invertebrates:

 Lancelets, sea squirts, Hagfishes

 All others are vertebrates

Chordates

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Subphylum: Vertebrata

• Vertebrates have endoskeletons:

– cranium (skull)

– backbone - series of vertebrae

What is characteristic of vertebrates?

chordate

Tunicates Lancelets Hagfishes

Lampreys

Cartilaginous fishes

Bony fishes

Amphibians Reptiles

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 first fish (about 542 million years ago)

 Lacked jaws ex Hagfish and Lampreys

 two major groups of fish with jaws:

 Cartilaginous fishes (sharks and rays) skeleton - cartilage

 Bony fishes -skeleton - hard calcium salts

ex Ray-finned fishes, Lungfishes, Lobe-finned fishes

 Aquatic adaptations: fins, gills

 lateral line system – detects vibrations

 Bony fish have swim bladders- gas-filled sacs - buoyancy

 Cartilaginous fish must swim – no swim bladder

Fishes How is the skeleton of a shark different from a bony fish?

How are fish adapted for an aquatic life?

Operculum

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Amphibians

 first vertebrates to colonize land

 Descended from fishes - had lungs and fins with muscles

(similar to lobefinned fish )

 aquatic and terrestrial adaptations

 need water to reproduce

 Undergo metamorphosis

Ex frogs, salamanders

Why are amphibians not fully adapted for a terrestrial life?

Lobe-finned fish

What group of fish are thought to have evolved into the amphibian group?

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 Reptiles, birds and some mammals produce amniotic eggs -

fluid-filled bag surrounded by membranes - embryo develops

inside

 Fully adapted to life on land:

 Amniotic eggs

 Scaled, waterproof skin

Ex Snakes, Lizards, Turtles, Crocodiles, Alligator (birds)

Dinosaurs

Reptiles

Are reptiles fully adapted for terrestrial living? Explain?

Explain what an amniotic egg is and in what vertebrate groups are

these eggs seen?

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 birds evolved from dinosaurs.

 ectotherms = “cold-blooded,” - obtain body heat from

environment

survive on <10% of the calories required by a bird or mammal

birds are endotherms, maintaining a warmer, steady body

temperature

Reptiles

What is the difference between ectothermy and endothermy?

What vertebrates are ectothermic? Endothermic?

Crocodile Lizard

Turtle

Dinosaur

Birds

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 adaptations that make them light for flight:

 Honeycombed bones

 One ovary

 beak instead of teeth

 wings adapted for flight, powered by breast muscles anchored to breastbone

Birds

How are birds adapted for flight?

 first mammals ~ 200 mya - small, nocturnal insect-eaters

 Mostly terrestrial although dolphins, porpoises, and whales - aquatic

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 three groups of mammals:

 Monotremes: egg-laying mammals

 Marsupials : pouched mammals with a placenta

 Eutherians ,:placental mammals