Invertebrates

Invertebrates

Invertebrates

• Invertebrates

– 1. Animals without a backbone
– 2. Come in many different shapes and sizes

Bilateral Symmetry

• 1. Bilateral symmetry

– 2 similar halves
– If you draw a line there

are 2 similar halves on
each side

Radial Symmetry

• 2. Radial symmetry

– Body parts are

arranged in a circle
around a central point

Asymmetrical

• 3. Asymmetrical

– No symmetry

3 Types of Symmetry

Multiple Choice

What type of symmetry does the organism have?

• Asymmetrical

• Radial

• Bilateral

Multiple Choice

What type of symmetry does the organism have?

• Asymmetrical

• Radial

• Bilateral

Multiple Choice

What type of symmetry does the organism have?

• Asymmetrical

• Radial

• Bilateral

Sponges

• Phylum: Porifera
• 1. Simplest

animals

• 2. Asymmetrical

•Water enters the sponge through its
pores.

•Then the water flows into the central
cavity and out the top of the sponge
through a hole called a osculum

Cnidarians

• Phylum: Cnidaria
• 1. Cnidaria means “nettles” Nettles are plants

that release stinging barbs in the skin

• 2. More complex than a sponge

Multiple Choice

What type of symmetry does the organism have?

• Asymmetrical

• Radial

• Bilateral

Cnidarians

Cnidarians

• “Catching Lunch”
• 7.All cnidarians have

long tentacles
covered in stinging
cells that catch small
fish and other
organisms by having
these stinging cells
that release
paralyzing toxin

Flatworms

• 1. Simplest group of

worms “Planarians”

• 2. Bilateral symmetry
• 3. Have a head and

eye spots

Planarians

1. Small- usually size of

your fingernail

2. Live in water and land

3. Predators (eat on other
animals or their parts)

Flukes and Tapeworms

• 1. Parasites

• 2. Live inside other

animals bodies

• 3. Host is usually killed

Roundworms

• 1. Have a simple

nervous system and a
primitive brain

• 2. Parasites
• 3. Live in their host
• 4. Pinworms and

hookworms infect
humans!

Multiple Choice

An example of a Parasite is...

• Lion

• Whale

• Mosquito

• Rabbit

Multiple Choice

True or False... A Parasite lives on or inside other animals.

• True

• False

Annelid Worms

• Phylum: Annelida

• Characteristics
• 1. Segments- identical or almost identical

repeating body parts

• 2. Brain found in the head and a nerve cord that

connects the brain to the ganglia

Mollusks

• 1. Phylum: Mollusca
• 2. Second largest

phylum of animals

• 3. Includes

– Snails
– Slugs
– Clams
– Oysters
– Squid
– Octopuses

Mollusks Characteristics

• 1. Most mollusks live

in the ocean

• 2. Some live in fresh

water

• 3. Soft body
• 4.Usually covered by

a shell

Arthropods

Arthropods

75% of all animals are arthropods

Characteristics of arthropods
•
1. Jointed limbs

•
2. Segmented body with specialized
parts

•
3. Well-developed nervous system

Jointed Limbs

1.

Jointed limbs gives
arthropods their names

2.

“Arthro” means joint

3.

“Pod” means foot

4.

Jointed limbs are arms,
legs, or other similar
body parts

5.

Jointed limbs let
arthropods to move
easily

Segmented and Specialized

•4. Exoskeleton- external
(outside) skeleton on
arthropods made of protein
and chitin

A. does the same thing as

an internal skeleton

B. allows the animal to

move

C. all muscles attach to

the exoskeleton and move
that part of the animal when
the muscles contract

D. acts like a suit of armor

to protect internal organs and
muscles

Segmented and Specialized

• 5. All arthropods have a head and a well

developed brain

• 6. Some arthropods can detect light but

can not form an image

• 7. Some arthropods can see images

because they have compound eyes
– Compound eyes- are made of identical light-

sensitive cells

Insects

• 1. Largest group of arthropod

• 2. have 6 legs and exoskeleton

• 3.Insects are beneficial when they

– A. pollinate

• 4. Insects are harmful when they

– A. eat crops
– B. carry diseases

Insect Development

• Metamorphosis- the development of an

insect from an egg to an adult

Multiple Choice

List the four stages of the complete metamorphosis life cycles in the correct order. 

• egg, pupa, larva, adult

• egg, larva, pupa, adult

• adult, egg, larva, pupa

• adult, egg, pupa, larva

Aracnids

• 1. Have 8 legs and exoskeleton

Crustaceans

• 1. crabs, lobsters, shrimp, krill,

Multiple Choice

It has 8 legs so it is an...

• Tentacles

• Insect

• Arachnid 

• Crab

Echinoderms

1. Phylum: Echinodermata
echinoderm means “spiny skinned”

Includes star fish, sea urchins, sea cucumbers,
brittle stars, and sand dollars

• Characteristics - Live on the sea floors &

have endoskeletons

Multiple Choice

What type of skeleton does an echinoderm have?

• exoskeleton

• jackskeleton

• endoskeleton

• external skeleton

The End!

Invertebrates