Introduction to animals

Chapter 12

Animal Characteristics Animals are multi-celled animals, whose cells

carry out many functions. Animals have specialized structures called

nuclei and other organelles. Animals are consumers, and rely on their

environment for food. Animals digest food and move the

macromolecules from food into their cells. Most reproduce sexually, some asexual. Animals are able to move from place to place

Adaptations for getting energy Over years animals have adapted to eating

whatever food is available to them in their environment.

Herbivores- eat only plants and plant parts. They eat more often and in greater amounts because plants don’t supply much energy.

Carnivores- these animals only eat other animals. Meat gives more energy and these animals do not eat as often.

Omnivores- are animals that that eat both plants and flowers.

Physical & Behavioral adaptations

Some animals have adapted physically to their environment. This includes camouflage, armored skin and venom for protection.

Some animals use behavioral adaptations to avoid predators, like when a squid shoots ink to avoid a predator.

Animal classification When classifying animals we look at some

major characteristics. Vertebrae- this is a bone structure that

supports and protects the spinal chord of animals.

The spinal chord connects the brain to every nerve in the body.

Invertebrates- are animals without a backbone. 97% of all animal species are invertebrates.

These animals have other protective structures, like shells and exoskeletons.

Animal classification Symmetry-this deals with the way an animals

body parts are arranged. An animal with an irregular shape, like a sponge

is considered asymmetrical. Radial symmetry- body parts are arranged

around a center point. Like hydra, or sea urchins.

Bilateral symmetry- here body parts on either side of the body are similar.

H.W pg 339 ques. 1-4

Sponges & CnidariansInvertebrates

Sponges play an important role in their environments.

They serve as food for fish and other sea creatures.

They also contain photosynthetic bacteria that produce oxygen in the water and removes wastes from the sponge.

It is being shown that sponges have medicinal values as well. They are being used to make antibiotics to fight bacteria, and also arthritis.

Sponges Sponges range in size from very small, to

the size of a small car. They could be symmetrical or

asymmetrical, and adult sponges live in one place for a long time before they are moved by waves or strong currents.

These sponges that stay in one place are called sessiles, and are usually found in large colonies of sponges.

Sponge body structure

A sponge has a hollow body that is open at one end and closed at the other.

The outside of the body contains small holes called pores. They have no tissues or organs.

Sponges have sharp spicules, that are spike like to held ward off predators.

Also, they could be made of spongin, which is a skeleton of fibrous material that also serves for protection.

Food and reproduction of Sponges They obtain food by cycling bacteria,

protists, and algae through their pores. Most species of sponges are

hermaphrodites, and produce both sperm and eggs. (sexual reproduction)

A sponge cannot fertilize its own egg. When an egg is fertilized it turns into a ciliated larva.

Some reproduce by budding. (asexual)

Cnidarians

These include hydra, jellyfish, anemones, and man of wars.

They live in salt water and fresh water, and some live as individuals or they live in colonies.

They can have a polyp body form, shaped like a vase, or a medusa shape or a bell shape.

Cnidarians All of these have one body opening and

radial symmetry. They have 2 body layers, where a sponge only has one.

They have tissues that form a digestive cavity. Each cell is able to take Oxygen from the water and convert it to CO2.

They have nerve systems called nerve nets, that carry impulses throughout its body.

Cnidarians

Most of these have tentacles that have stinging cells for protection from predators.

Some organisms like small fish live symbiotically with the cnidarians in among their tentacles.

They are predators and can stun and poison their prey using their stinging cells.

Cnidarians They reproduce sexually and asexually. Polyp forms reproduce asexually by budding and

sexually by producing sperm and eggs. Medusa forms release sperm or eggs into the

sea. When they fertilize it drops to the ground and forms as a polyp. (sexual stage)

After this, a medusa buds off the polyp and the cycle begins again.( asexual stage)

H.W. pg 360 ques. 1-10

Worms Worms are invertebrates with soft bodies

and bilateral symmetry. They have 3 tissue layers that are

organized into tissues and organ systems. Flatworms have flattened bodies, and are

free living or parasitic in nature. Flatworms include planarians, flukes, and

tapeworms.

Flatworm

Planarians Planarians are free living worms with

triangular shaped heads that have 2 eye spots.

It has a one body opening, a mouth, and a pharynx that connects it to its digestive system.

They are covered in cilia that help it move, and range from 3-30mm in length.

They reproduce sexually by dividing in two, and sexually by the use of sperm and ova.

Flukes All flukes are parasites, that mostly

reproduce sexually. The male fluke deposits his sperm in the

female and the female lays the eggs inside the host.

The host passes the eggs in its feces or urine.

The newly born worms can then burrow into the skin of hosts such as humans and cause serious disease.

Tapeworms These are parasites also, but the use

hooks to attach itself to the digestive track of its host.

They have no mouth or digestive system, but it absorbs food from the host.

They grow by producing a new segment that is placed immediately behind its head.

Each segment has both male and female organs. When a segment gets filled with fertilized eggs it breaks off and passes out of the host.