Animal DiversityRowel P. David

BiodiversityATHS Science for Grade 8

Sir Rowel P. David

The Kingdoms of Life Biologists have organized living things into

large groups called Kingdoms. Biologists group organisms into six Kingdoms

based on RNA and DNA sequencing and similarities: Cell Type

Organisms are either prokaryotes or eukaryotes. Cell Walls Body Type

Organisms are either unicellular or multicellular. Nutrition

Organisms are either autotrophs or heterotrophs.

The 6 Kingdoms of Life

The 3 Domains of Life The domain thought to be the oldest is

Bacteria, which is composed of the organisms in the Kingdom Eubacteria.

Archaea is the second prokaryotic domain and is also composed of single kingdom Archaebacteria.

The third domain, Eukarya, contains all four of the eukaryotic kingdoms: Animalia (animals), Fungi (fungi), Plantae (plants), and Protista (protists).

Each animal phylum has a unique body plan. Vertebrates have an internal segmented backbone. Invertebrates do not have a backbone. Invertebrates encompass most animal groups.

Differences in body plans result from differences in the expression of Hox genes.

– Hox genes tell embryonic cells which body part to become.

– Mutations in Hox genes led to the vast diversity of animal species.

head tail

headtail

fruit fly genes

human HOX-B genes

Animals are grouped using a variety of criteria. Three criteria are used to categorize

animals. body plan symmetry

– tissue layers – developmental patterns

gastrovascular cavity

mouthmesoglea

oral arms

tentacles

blood vessels

brain

heartsmuscle

segment nerve cord

mouth

digestive track

There are two types of body plan symmetry.– bilateral symmetry: body divides equally along one plane

Animals with bilateral symmetry can be divided equally along only one plane, which splits an animalinto mirror-image sides.

– radial symmetry: body arranged in circle around a central axis

• There are two types of body plan symmetry.– bilateral symmetry: body divides equally along one plane

Animals with radial symmetry have body parts arranged in a circle around a central axis.

The current organization of the animal kingdom shows some unexpected relationships.

• Technological advancementshelp to clarify evolutionaryrelationships.

Kingdom Animalia

Kingdom Animalia Animals are complex multicellular heterotrophs.

Their cells are mostly diploid, lack a cell wall, and are organized as tissues.

Animals are able to move rapidly in complex ways.Movement enables animals to avoid predators and to look for food and mates.

Kingdom Animalia Most animals reproduce

sexually. Almost all animals (99%) are

invertebrates; they lack a backbone.

Of more than 1 million living species, only about 42,500 have a backbone; they are referred to as vertebrates.

The animal kingdom includes about 35 phyla, most of which live in the sea.

Kingdom AnimaliaCharacteristics

HeterotrophsEukaryoticMulticellularNo cell wall, no chloroplastsMotileSense Organs

9 phyla we will mentionPorifera—spongesCnidaria—jellyfish, sea anemones,

coralPlatyhelminthes—flatwormsNematoda—roundwormsAnnelida—earthwormsMollusca—shelled animalsArthropoda—insects, spidersEchinodermata—spiny-skinnedChordata—vertebrates (and

others)

A comparison of structure and genetics reveals the evolutionary history of animals.

Protostomes and deuterostomes are the two major radiations on the animal phylogenetic tree.

Porifera CnidariaPlatyhelminthesAnnelidaMollusca NematodaArthropoda

EchinodermataChordata

RADIAL

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Phylum Porifera(sponges) Asymmetrical Pores—filter feeders Not motile (sessile) Provide habitat for other animals Eaten by starfish and some fish Most primitive animal

Phylum Cnidaria(jellyfish, sea anemones, coral) Digestive cavity called a

coelenteron Radial symmetry Predators-feed on crustaceans Corals provide important

habitat for fish Coral used for decoration and

threatened by pollution All have stinging cells

Phylum Platyhelminthes(planarians, tapeworms, flukes) Bilateral symmetry Cephalization- head and brain Acoelomate- no body cavity Incomplete digestive system

(one opening) Some are parasites in digestive

tract In early 1900’s models ate

them to be thin—YUK!

Phylum Nematoda(roundworms) Also called nematodes Complete digestive system-

separate mouth and anus (2 openings)

Pseudocoelomate Decomposers, predators

(bacteria, inverts) Eaten by insects, mice Beneficial to garden by eating

insects

Phylum Annelida(segmented worms) i.e. earthworms, leeches True coelom Sensitive to vibrations on

ground-rain Prey for robins, shrews, jays,

snakes Leeches have cornified knobs

to break skin, anticoagulant and anesthetic

Phylum Mollusca(shelled…sometimes) i.e. snails, slugs, clams, mussels, scallops,

oysters, octopus and squid Variety in form Giant squid = sea serpent Introduction of garden snails

Phylum Arthropoda(jointed legged animals) i.e. insects, spiders and

scorpions, shellfish (crustaceans), centipedes (1 pr legs per segment), millipedes (2 pr)

Exoskeleton Metamorphosis Pheromones Molting

Phylum Echinodermata(spiny-skinned) i.e. sea stars = starfish, sea urchins Water vascular system Tube feet Important predators

Phylum Chordata(includes the vertebrates) i.e. fish, sharks, amphibians, reptiles,

birds, mammals Notochord, nerve cord, gill slits, tail

Kingdom Animalia

Kingdom Animalia Animals are complex multicellular heterotrophs.

Their cells are mostly diploid, lack a cell wall, and are organized as tissues.

Animals are able to move rapidly in complex ways.Movement enables animals to avoid predators and to look for food and mates.

Kingdom Animalia Most animals reproduce

sexually. Almost all animals (99%) are

invertebrates; they lack a backbone.

Of more than 1 million living species, only about 42,500 have a backbone; they are referred to as vertebrates.

The animal kingdom includes about 35 phyla, most of which live in the sea.

Kinds of Animals

SpongesThe only animals that do not have tissues, but they do have specialized cells.

CnidariansMostly marine animals; they include jellyfish, sea anemones, and corals.

Kinds of AnimalsFlatworms

Have flat, ribbon-like bodies.

Some are parasitic and live inside the bodies of animals.

Others are free-living and may live in soil or water.

Kinds of AnimalsRoundworms

Nematodes are small worms that have long, very slender bodies.

Some are free-living in soil or water, while others are parasites of animals and plants.

Kinds of Animals

Segmented WormsAnnelids live in both

water and soil and include the familiar earthworm.

Bristled marine worms are segmented worms, as are leeches, which can be blood-sucking parasites.

Kinds of Animals

MollusksHave a saclike cavity called a

coelom that encloses internal organs.

Are very diverse aquatic and terrestrial animals.

They include snails, oysters, clams, octopuses, and squids.

Most have a hard external skeleton (a shell).

Kinds of Animals

ArthropodsThe most diverse of all animals.

They have an external skeleton, jointed appendages with antennae and jaws.

Kinds of Animals

EchinodermsIncludes sea stars, sea urchins, and sand dollars.

Many are able to regenerate a lost limb.

Kinds of AnimalsInvertebrate Chordates

Aquatic animals that have much in common with vertebrates, though they do not have a backbone.

Some are swimmers that resemble fish, while others live attached to a rock or other object.

Kinds of AnimalsVertebrates

Have an internal skeleton made of bone, a vertebral column (backbone) that surrounds and protects the spinal cord, and a head with a brain contained in a body skull.

Includes mammals, fish, birds, reptiles, and amphibians.

Kinds of Animals