chapter 23: the animal kingdom - allied american...

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Chapter 23: The Animal Kingdom Lecture Outline Enger, E. D., Ross, F. C., & Bailey, D. B. (2012). Concepts in biology (14th ed.). New York: McGraw-Hill. 1

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 23-2

What is an animal?

Eukaryotic Multicellular

– Have specialized cells – Many have sensory cells that detect changes in

the environment. Lack cell walls Heterotrophic Most can move Most reproduce sexually


Variety of Animals

See Figure 23.1


The Evolution of Animals

Early animals were all aquatic. – The first animals were likely small organisms that

floated/swam in the ocean or worms that lived on the ocean floor.

– These animals didn’t need to Deal with rapid or extreme environmental changes Deal with dehydration Expend energy to keep cells in osmotic balance

Terrestrial animals appeared relatively recently. – Arthropods and vertebrates have been the most successful.

99.9% of all animals are invertebrates. – Invertebrates lack a backbone. – Vertebrates have a backbone.


Animal Evolution

See Figure 23.2


Temperature Regulation

Body temperature impacts the rate of metabolic activity.

Poikilotherms – Body temperature varies with environmental temperature – Metabolic rate decreases as temperature decreases – Also called ectotherms – Regulate body temperature behaviorally (sunning, moving) – Insects, worms, reptiles


Temperature Regulation

Homeotherms – Maintain a constant body temperature – Body temperature usually higher than

environmental temperature – Have high metabolic rates – Have higher energy needs than poikilotherms – Also called endotherms


Regulating Body Temperature

See Figure 23.3


Body Plans

Animal bodies conform to a few basic body plans.


Symmetry

Asymmetry – No pattern to individual parts – Only occurs in sponges

Radial symmetry – Body constructed across a central axis – Dividing the body in any plane along that axis results in two

identical parts – These animals do not have a “head” – Starfish, jellyfish

Bilateral symmetry – Both sides of a single plane are mirror images – These animals have a head – Move head-first (cephalization)


Radial and Bilateral Symmetry

See Figure 23.4


Embryonic Cell Layers

Animals differ in the number of cell layers of which they are composed.

– These layers are established and most easily seen in the embryonic stage.

Sponges have no body layers. Diploblastic

– Two body layers Endoderm

– Gives rise to inner hollow layer involved in processing food Ectoderm

– Gives rise to outer protective layer

– Jellyfish



Triploblastic – Have three layers

Endoderm – Gives rise to lining of digestive tract

Mesoderm – Gives rise to muscles and connective tissue

Ectoderm – Gives rise to skin and nervous system

– All other major groups are triploblastic.



See Figure 23.5


Body Cavities

Many animals have a body cavity that separates the outer body wall from the gut.

– Called a coelom

Acoelomate – Contain no body cavity – Sponges, jellyfish, and flatworms

Pseudocoelomate – Located between the lining of the gut and the outer body wall – Nematodes


Body Cavities

Coelomate – This is the cavity that contains the digestive,

excretory, and circulatory organs. – Organs are held in place by sheets of connective

tissue called mesenteries. – The presence of the coelom allows for separation

of inner organs and body-wall muscles. – This allows the organ systems to be more

specialized.


Body Cavities

See Figure 23.6


Segmentation

Segmented animals have bodies that are separated into several units.

– These units run along the anterior to posterior axis of the animal.

Associated with specialization of body parts Annelids, arthropods, and chordates

– Annelid segments are all very similar. – Arthropods have specialized head segments.

Posterior segments have legs and appendages. – Chordate segments are most obvious in the vertebral

column and musculature.


Segmentation

See Figure 23.7


Skeletons

Skeletons are body parts that provide support. – Serves as a scaffolding for the attachment of

organs – Provides a place for muscles to attach – Most important in terrestrial animals


Skeletons

Types of skeleton – Endoskeleton — internal

Vertebrates Grows as the animal grows

– Exoskeleton — external Arthropods Hard and jointed Shed and regenerated as animal grows

– Water skeletons Fluid-filled coeloms Compressed by muscles to facilitate movement


Skeletons

See Figure 23.8


Marine Lifestyles: Zooplankton

A mixture of different kinds of small animals Drift with currents Feed on phytoplankton and other

zooplankton 70% are crustaceans

– Copepods, krill, etc.


Marine Lifestyles: Nekton

Includes many kinds of aquatic animals that can swim against the current – Go where they want to

Carnivores – Feed on plankton or other nekton

Jellyfish, squid, cuttlefish, shrimp, sharks, bony fish, turtles, sea snakes, aquatic birds, and mammals


Marine Lifestyles: Benthic Animals

Bottom-dwelling animals Includes

– Segmented worms, clams, snails, lobsters, crabs, shrimp, starfish, sea urchins, several kinds of fish

Two types – Those that move to find food – Filter feeders

Attached to objects Are sessile Create currents with cilia or use appendages to draw food to

them


Marine Lifestyles: Benthic animals

Reproduction is difficult for sessile animals because they cannot move. – Sperm swim to the eggs. – Fertilized egg develops into mobile larva

Enables sessile animals to disperse Uses a different source of food from adults to minimize

competition


The Life Cycle of an Oyster

See Figure 23.9


Primitive Marine Animals: Porifera

Similar to colonial protozoa Have two layers of cells

– All cells come in contact with the environment. – Each individual cell gets its nutrition directly from the water.

Adults are sessile (non-motile). Most are asymmetrical. Have spicules in a jelly-like material

– Spicules are made of calcium carbonate, silicon dioxide, or protein.

Reproduce asexually by fragmentation or budding Reproduce sexually by external fertilization

– Sperm and egg unite in the water – Fertilized egg develops into free-swimming ciliated larva


Sponge Structure and Function

See Figure 23.10


Primitive Marine Animals: Cnidaria

Jellyfish, corals, and sea anemones Have two layers of cells

– Jelly-like material in between cell layers Show radial symmetry Have a single opening that leads to digestive

cavity – Opening surrounded by tentacles

Contain specialized cells called nematocytes that can sting and paralyze

The cells that produce nematocytes are called cnidocytes.


Phylum Cnidaria

See Figure 23.11


Cnidaria

Exhibit alternation of generations

– Have both sexual and asexual reproduction

– Medusa is the free-swimming adult stage that reproduces sexually.

– Polyp is a sessile larval stage that reproduces asexually.

See Figure 23.12


Ctenophora: The Comb Jellies

See figure 23-13


Platyhelminthes

Also called flatworms Bilaterally symmetrical Triploblastic Lack a coelom Have one opening to the gut Have no circulatory or respiratory systems

– Their flat body allows for the diffusion of gases between environment and all cells.


Platyhelminthes

Three basic types – Free-living flatworms (planarians)

Bottom-dwellers in aquatic environments Some live in moist terrestrial habitats Carnivores or scavengers that feed on dead organisms

– Flukes Parasitic

– Tapeworms Parasitic


Platyhelminthes

See figure 23.14


Flukes

All are parasites (some external, most internal). Life cycles usually involve a vertebrate and

invertebrate host. Example: Schistosoma mansoni


Life Cycle of Schistosoma mansoni

See figure 23.15


Tapeworms

All are parasites. Life cycles involve two hosts—an herbivore

and a carnivore (both vertebrates).


Life Cycle of a Tapeworm

See figure 23.16


Nematoda

Also called roundworms Unsegmented Have an outer epidermis covered by a thick, flexible

cuticle Triploblastic Have a pseudocoelom Digestive tract is open at two ends

– Mouth at one end, anus at the other Live in diverse habitats

– Water, soil, as parasites Examples of parasitic forms

– Pinworms, heartworms, hookworms


Nematode Worms

See Figure 23.17


The Life Cycle of a Hookworm

See Figure 23.18


Annelida

Segmented worms Bilaterally symmetrical Have bodies with repeating segments

– Most segments are similar to one another. – Segments containing head, reproductive, and digestive

structures are specialized.

Each segment has a coelom. Have well-developed muscular, circulatory,

digestive, excretory, and nervous systems


Annelida

See figure 23.19


Types of Annelida

Polychates – Primarily benthic, marine worms – Have paddle-like appendages on each segment – Have heads with sense organs and a mouth – Are filter feeders – Have separate sexes that reproduce sexually

Produce larva called trochophores


Types of Annelida

Oligochates – Live in soil or freshwater – Earthworms – Do not have appendages or a well-defined head – Are hermaphroditic – Eat dead organic matter, generate air spaces in

soil


Types of Annelida

Leeches – Live in freshwater or moist terrestrial

environments – Have suckers that allow them to hold on to

objects – Feed on the blood of vertebrates


Annelids

See Figure 23.20


Mollusca

Live in marine, freshwater, or terrestrial environments – Majority live in the ocean

Have a coelom Reproduce sexually

– Some are hemaphroditic Have a soft body enclosed by a hard shell


Mollusca

Most are slow moving, benthic animals Most are herbivores or saprophytes Have free-living larval forms that aid in dispersal Have three body regions

– Mantle, foot, and visceral mass – Visceral mass contains digestive, circulatory, and

reproductive organs. – Most have a radula with teeth.

Used to scrape surfaces for food


Mollusca

See figure 23.21


Types of Mollusca

Chitons – Have a series of shells on their backs – Live attached to rocks – Feed on algae

Bivalves – Have two shells – Filter feeders without a radula

Snails – Have coiled shells – Slugs are snails without shells

Octopus and squid – No outer shell


Types of Mollusca

See figure 23.22


Arthropoda

Most successful types of animals Have exoskeletons made of chitin

– Must shed to grow Have segmented bodies

– Segments are highly modified. – Most segments have paired appendages. – Body and appendages are segmented.

Have well-developed nervous, muscular, digestive, respiratory, circulatory, and reproductive systems


Arthropoda

See figure 23.23


Types of Arthropods

Crustaceans – All aquatic – Omnivores

Millipedes and centipedes – Long bodies with many legs

Arachnids – Spiders, mites, and ticks

Insects – Have a head, thorax, and abdomen – Have 3 pairs of legs – Most have wings


Arthropods

See Figure 23.24


Echinodermata

Are dueterostomates – Anus develops before mouth

All are marine, benthic animals Most are free-living Most are carnivores or detrivores


Echinodermata

Display radial symmetry – Have five arms that project from a central axis – Larva display bilateral symmetry.

Have a water vascular system – Water is taken through a pore on the top, then

moves through a series of canals. – Aids in movement of the animal

Have a hard, jointed internal skeleton


Echinoderms

See Figure 23.25


Types of Echinoderms

Starfish – Some are carnivores that

eat clams

Sea cucumbers – Sausage-shaped

organisms – Lie on the bottom or

burrow in mud – Some are detrivores,

others are filter-feeders.

Crinoids – Sessile and stalked – Have five arms – Called sea lilies – Filter feeders

Brittlestars Sea urchins


Types of Echinoderms

See figure 23.26


Chordata

Have a hollow nerve cord down the back of the body

Have a flexible rod just beneath the nerve cord – Called the notochord

Have a tail that extends beyond the anus Have a pharynx Most are vertebrates

– Notochord only present during embryonic stage


Invertebrate Chordates

See Figure 23.27


Types of Aquatic Vertebrates: Fishes

Hagfish and lampreys are the most primitive fish.

– Hagfish are marine scavengers.

– Lampreys are mainly marine (some freshwater). Adults suck blood

from larger fish.

See Figure 23.28



Sharks and rays – Have an internal

skeleton made of cartilage

– Have no swim bladder, so must constantly swim or they sink

– Rays feed along bottom. – Sharks are predatory.

See Figure 23.29



Bony fish – Have skeletons

composed of bones – Have a swim bladder

that controls their density Allows them to

remain at a given depth without swimming

See Figure 23.30


Adaptations to Terrestrial Life

Animals that live on land have to overcome certain problems. – A moist membrane for gas exchange – Means of support and locomotion on land – Methods to conserve water – Means of reproduction and embryonic

development that doesn’t require water – Methods to survive rapid and extreme climate

changes


Terrestrial Arthropods

Exoskeleton – Waterproof, which

reduces water loss Have an internal

respiratory system – Tracheal system of thin-

walled tubes – Provides a large surface

area for gas-exchange – Have small openings to

the outside, reducing water loss

See Figure 23.31


Terrestrial Arthropods

Have Malpighian tubules – Thin-walled tubes that surround the gut – Allows for reabsorption of water

Reproduce by internal fertilization – Protects sperm and egg from drying out

Can reproduce rapidly when conditions become favorable


The Life History of a Monarch Butterfly

See Figure 23.32


Terrestrial Vertebrates

Endoskeleton – Provides support in the air – Provides places for muscle attachment

Allows for movement on land

Appendages are necessary for movement on land.


Amphibians

Lungs – Allow for the exchange of oxygen and carbon

dioxide from the air – Amphibians also breathe through their skin.

Skin must remain moist

External reproduction in water Frogs and salamanders


Amphibians

See Figure 23.33


Reptiles

Have internal lungs Have waterproof skin Have water-conserving

kidneys Reproduce via internal

fertilization – Fertilized egg is encased

in an amniotic egg – Protects the young from

dehydration and injury Young need water to

develop.

See Figure 23.34


Reptiles

See Figure 23.35


Birds

Skin, lungs, and kidneys reduce water loss Reproduction involves internal fertilization.

– Produces a shelled amniotic egg

Are homeothermic and have feathers – Have high metabolic rates – Feathers insulate and enable flight. – Must incubate eggs

Flight allows – Movement with less expenditure of energy – Quick escape from predators – Ability to cross barriers


Birds

See Figure 23.36


Mammals

Homeotherms – High, constant body temperature – High metabolic rate

Have waterproof skin, water-conserving lungs and kidneys

Have hair as insulation Provide milk to their young


Types of Mammals

Monotremes – Egg-laying mammals – Young lap milk from mother’s fur

Marsupials – Internal development of young – Young complete development in mother’s pouch

In pouch, young drink milk from nipple

Placental – Internal development of young

Stay in mother longer Embryo attached to uterus via a placenta

– Young are born in a more advanced stage Still rely on mother’s milk


Mammals

See Figure 23.37

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