INVERTEBRATE DIVERSITY

Animal diversity is very intense!

Blue-ringed octopus – one of the deadliest animals in the ocean.

Lives in shallow reefs and tide pools from Japan to Australia.

• Octopi are incredibly intelligent.• They are masters of disguise, using

camouflage as a defense mechanism.• The blue-ringed octopus injects

poison into its prey or into the vicinity of its prey.• It also uses a different substance for

self-defense that is 10,000 times more lethal than cyanide.

MIMIC OCTOPUSCan look like a venomous sea snake, a toxic flatfish, a sea anemone, or a jellyfish!

Only a mimic octopus can mimic multiple toxic animals.

Characteristics of Animals

• Eukaryotic

• Multicellular (eliminates the protists)

• Moveable (at least one time in it’s life cycle)

• Heterotrophs that ingest their food within their bodies after ingesting organisms, dead or alive, whole or by the piece.

The animal way of life

• Animal cells lack cell walls that provide support to plants and fungi.

• Animals are held together by extracellular proteins.

• Most have muscle cells for movement and nerve cells for conducting impulses.

• Most animals are diploid and reproduce sexually.

• Egg and sperm are the only haploid cells.

• (Ants, bees, and wasps have some males that develop from unfertilized eggs that are haploid)

• Sperm and egg join to form a zygote.

• The zygote develops into a multicellular adult.

• The zygote divides repeatedly in half until there is a ball of cells called a blastula.

• One side of the ball of cells folds inwards forming a gastrula.

• If the gastrula becomes an anus, the animal is a deuterostome (echinoderms and chordates). A mouth develops from a second opening later.

• If the gastrula becomes a mouth, the animal is a protostome.

Larva

• After gastrulation, many animals develop directly into adults.

• Others develop into one or more larva stages first.

• Larva undergo metamorphosis (major body change) in developing into an sexually reproducing adult.

• Animals have been around for roughly a billion years.

• The fossil record shows a giant explosion of animal diversity in the Cambrian era (approx. 542 million years ago).

THERE IS NO “ONE” BEST ANIMAL

Each form, each adaptation, and each body plan has advantages and

disadvantages.

Phylogeny • The evolutionary

history of animals (where they come from).

• The phylums are on the far right.

• The branch points indicate a common ancestor between the two branches.

•Animal body plans vary in symmetry, body cavity, and number of germ layers.

• First branch: true tissues or no true tissues.

• If there are no true tissues, then the animal is a sponge.

• If there are true tissues, then the animal is a eumetazoan.

Next Division – Body Symmetry

Radial Symmetry Bilateral Symmetry

Radial Symmetry

• Example: Sea Anemone

• No matter where you cut through it , it will be the same on either side.

• Exampe: Cnidarians.

Radial Symmetry

• The animal has a top and a bottom but lacks front and back or right and left sides.

• Radial animals are sedentary or passive drifting.

Bilateral Symmetry

• If you cut the organism down the middle, there is a definite right side and a definite left side.

Bilateral Symmetry

• These animals have mirror-image right and left sides, a distinct head and tail, and a back (dorsal) and belly (ventral) surface.• They also have a brain, sense organs and

mouth located in the head.• Facilitates mobility; the animals meets its

environment head-first.

What does the gastrula become?

• If the gastrula becomes an anus, the animal is a deuterostome.

• If the gastrula becomes a mouth, the animal is a protostome.

Tissues• Outer Layer –

Ectoderm• These are the outer

coverings that become your skin or in some organisms becomes nerves and the brain

Endoderm

• The endoderm is in the middle and becomes the linings of the organs.

Mesoderm

• The mesoderm becomes the muscle and bones.

Animals body plans vary in organization of tissues.

Phylum Poriferameans “pores”

water moves through the pores

flagella on theInside driving he water throughwhich isfull ofparticulates.

Purple Tube

Sponge

Porifera - Sponges

• Sponges lack true tissues.

• In other animals, cell layers formed during gastrulation give rise to tissues and organs.

• Some animals have only ectoderm and endoderm, but most animals also have mesoderm.

Glass Sponge – Venus Flowering Basket

Silica Spicules

Cnidarians

Cnidarians – True Animals

• Sea anemones

• Jelly fish

• Sea anemone – tentacles up and are fixed on the bottom

• “hydra” stage

• Tentacles containing “stinging cells.”

• In the jellies, the tentacles are facing downward.

• They have a mouth that also serves as an anus.

• Also have stinging cells.

• Called the “medusa stage.”

Body cavities of animals vary.

Flatworms• Example: Planaria

• Have simple eyespots.

• Mouth is located on their stomach.

• Can cut their head in half and it will generate two heads.

Tapeworms

• Tapeworm parasites are found in beef and pork and other animals.

• Tapeworm infections in humans are caused by eating raw or undercooked infected meat.

• The tapeworm larva develops in the human intestine and can grow up to 12 feet.

Tapeworms

Tapeworm (cont’d)

• Scolex on the anterior end to attach to their host.

• They do not have a “true” digestive system.

• They absorb nutrients through their flat-bodied skin.

• THEY CAN BE DOZENS OF FEET LONG.

Nematode Worms

• Longitudinal muscles• Over 500,000

species, many are parasitic.

• They have a true digestive system.

• Example: Heartworms in dogs.

Nematodes parasitic on Humans

• Ascarids (roundworms)

• Hookworms

• Pinworms

Heartworms in a Dog

Molluscs• All have a muscular

foot.

• All have a visceral mass containing most of the internal organs.

• Their mantle may secrete a shell to enclose the visceral mass.

• Gastropods – largest groups of mollusks and include snails and slugs.

• Most snails are protected by a single, spiral shell.

• In land snails, the lining of the mantle cavity functions as a lung.

• Slugs have lost their mantel and shell and have long colorful projections that function as gills.

Sea Slug

Bivalves• Shells divided into

halves that are hinged together.

• Examples: clams, oysters, mussels, and scallops

• Most are sedentary suspension feeders.

Cephalopods

• Octopi, squid, cuttlefish.

• Means “head-feet”

• They are found in all oceans and cannot live in fresh water.

• Agile predators!

• Large brains

• Beak-like jaws

Annelids – Segmented Worms

• Repeated parts – segments

• Example: earthworms and leeches

• They have an closed circulatory system.

Squid

Medicinal Leech

Arthropods

• Over a million species.• Crayfish, lobsters, crabs,

spiders, ticks, and insects.

• Success is due to segmentation, a hard skeleton, and jointed appendages

Structure of an Arthropod

Insects

Most successful of all animals!

• More than a million species of insects have been identified.

• Many can fly.

• Waterproof coating on the cuticle.

Protective Color Patterns

Mimicry