Simple Invertebrates

Sponges, jellyfish and coral, flatworms, roundworms, and

segmented worms too!

Phylum Platyhelminthes(Flatworms)

More complex than sponges and cnidarians. Organisms with long, flat body. Clearly defined head with mouth. Some have senses, a few even have eyespots. Some move freely. Live in ponds, streams, or in a host! Many are parasites

Flatworms:planarian

flukes

tapeworm

Characteristics:

Simplest of all worms 1 body opening Flat bodies

Hermaphrodites

Most flatworms are parasites

Reproduce- Asexually-

regeneration & fission

Sexually Cellular Level-

Organs 3 tissue layers

Endoderm Mesoderm Ectoderm

Planarians:

Triangular head with eyespots that sense light

Parasites

Feed on dead plant & animal matter

Reproduce asexually- Regeneration

Digestive system- Mouth Pharynx intestine

Tapeworms:

Long, flat ribbons

Parasites

Live in bodies of humans & animals

head has hooks that attach to the host

can grow up to

18 feet long!

Liver fluke:

Parasite

Live in the liver or blood of an animal host

Animal hosts: Snails Fish Humans

Humans can get liver fluke by eating raw or uncooked fish that contains the parasite.

Preventions?

Phylum: Nematoda (Roundworms)

Another step up the ladder! Live on land or in the water Some even have a simple nervous system. Some have a digestive system that runs through

the entire body -- with two openings, one for food to enter and one for wastes to leave.

Most are parasites. Some are harmless microscopic critters that live

in the soil.

Characteristics:

Examples: hookworm, heartworm, pinworm, Trichinella

Described as a “tube within a tube” First animals with a complete

digestive system two body openings: mouth & anus

Trichinella Parasite Lives in the muscle tissue of pigs Live and reproduce in the intestine of

the host.

Prevention? The disease is called Trichinosis

Hookworm:

Parasite Live in small intestine

where it enters the bloodstream

From the bloodstream it enters the lungs, coughed up, then swallowed and enters the digestive system.

Hookworm eggs are passed in the feces of an infected person.

Hookworm infection is mainly acquired by walking barefoot on contaminated soil.

Prevention?

Heartworm:

Parasite Enters the blood of a dog

through a mosquito bite! Worm moves to the heart

where they grow and reproduce.

They block the valves that lead to and from the lungs.

Prevention?

Pinworm: Parasite Adult lives in the

large intestine Female migrates to

the anal region to lay her eggs

Prevention?

Phylum: Annelid Live in fresh & salt

water, streams, and soil

Examples: Leech Earthworm

Most common Lubricus terrestris

Characteristics: Approximately 100

segments Outer layer made of

mucus to help the animal glide

Setae- tiny bristles that help in movement

Systems: Closed Circulatory system-

5 pairs of tube hearts

Digestive system- Mouth Pharynx Esophagus Crop Gizzard Intestine Anus

Nervous system- Ganglion Nerve cord

Respiratory system- No organs O2 enters through the

skin & CO2 leaves Reproductive

system- sexual Sperm is exchanged

at the clitellum Clitellum- the band

on the earthworm where the sex cells are located

How do earthworms help the environment?

After organic matter is digested, the earthworm releases waste from their bodies called castings.

Castings contain many nutrients that the plant can use.

Some people even use earthworm castings as garden fertilizer.

Enrich and improve soil for plants, animals & even humans.

Create tunnels in the soil by burrowing, which aerates the soil to allow air, water and nutrients to reach deep within the soil.

External Earthworm Lab

External Anatomy

Phylum Porifera(Sponges)

Simplest animals of all (some of the oldest too). All are aquatic (freshwater and marine). Only two layers of cells, no tissues or organs! Their skeletons are made of tiny spines called

spicules. Cannot move (grow attached to the bottom). Mostly filter feeders. Uses?

The mighty sponge!

Phylum Cnidaria (aka Coelenterata): Jellyfish and Coral

More advanced than sponges. (for example, they have tissues, but still no organs).

Their body is a hollow cavity with only one opening (for food AND wastes)!

Entirely aquatic (freshwater and marine). All have stinging cells, but not all can harm people. Some are pretty nasty predators. Others filter-feed

on small particles and organisms in the water.

Medusae vs. Polyps

MEDUSAE

Ex. Jellyfish A medusa is free-swimming. Most are solitary. Their opening is on the

bottom of their body.

POLYPS

Ex. Coral Polyps are like an upside

down medusa. Their opening is on the top

of their body. Coral polyps are tiny and live

in huge colonies of thousands.

Corals build their “home” as the colony grows larger and larger.

Jellyfish

Most jellyfish are harmless to people, although not so to small fish and other marine organims.

Portuguese man-of-war.Look out!

Corals: beautiful colonies of polyps.

More Cnidarians: hydra and sea anemones.Is it a medusa or a polyp?

Roundworms!

One teaspoon of garden soil may contain as many as 10,000 tiny nematodes (roundworms) in it!

Phylum Annelida(Segmented Worms)

Most complex worms of all. Tube-like body divided into segments. Sophisticated digestive system! (mouth, crop and gizzard,

intestine, anus) Many other specialized organs heart, blood vessels, nerve

cords, simple brains) Can move well. Some aquatic (leeches, clam worms), some terrestrial

(earthworms). Some are parasites (leeches), others are very important

decomposers (earthworms). Any other uses for annelids?

Phylum Annelida(Segmented Worms)

So NOW what do you know about the simple invertebrates?

Do you know the names of the five phyla of simple invertebrates?

Do you know the main characteristics of each of the five phyla?

Can you identify examples of animals in each of the five phyla?