Worms

Flatworms, Roundworms, and Segmented Worms

Science7

Characteristics of Worms

All worms share the following characteristics: Invertebrates Long narrow bodies without legs Tissues, organs, and organ systems (with

brain) Bilateral Symmetry (head and tail ends) Reproduction: Sexual and Asexual 3 Cell Layers

Ectoderm Mesoderm Endoderm

3 Major Phyla of Worms

There are 3 major phyla of worms:

Platyhelminthes = Flatworms

Nematoda = Roundworms

Annelida = Segmented Worms

Flatworms

From 2 Greek words: Platy means “flat” Helminthe means “worm”

Simplest of all worms Flattened bodies Most are parasites and get food from host

Flatworms: 3 Types

There are many kinds of flatworms: Planarians Tapeworms Flukes

Flatworms: Tapeworms

Tapeworms Lives in the intestines of animals

(including humans!) Uses hooks and suckers on its head to

dig into the lining of an organism’s digestive tract

Considered Parasitic Blocks the host’s intestines Steals valuable food and water

Can grow 10-12 meters in length

Life Cycle of A Tapeworm

Flatworms: Planarians

PlanariansScavengers

A feeding tube releases digestive juices to break down food.

THINK! – What type of digestion is this? Odor cells are found on the head

THINK! – What do the odor cells help with? Planarians have 2 photosynthetic

eyespots THINK! – What do the eyespots detect?

Watch Planarians :55

Flatworms: Flukes

Flukes Usually live in the

human liver Shape: Oval and

flat Size: 2mm -15 cm

Activity: Draw A Flatworm

Draw, color, and label the diagram of this flatworm in your guided notes.

Digestive Tract(red)

Roundworms

General Characteristics: Cylindrical bodies Contains a digestive system

Food enters at a mouth Waste exits through the anus

Roundworms: Trichinella

Trichinella Lives in muscular tissue of

pigs These worms reproduce in

the intestine of the host Female worms release hundreds

of immature worms carried in the bloodstream

These immature worms burrow in the surrounding tissue causing pain to the host

Roundworms: Hookworms

Hookworms Enter the body by burrowing

through the soles of feet Eventually ends up in the

intestines where they live off of blood

Roundworms: Pinworms

Pinworms Small white parasitic worms found in the

feces of babies Babies sometimes ingest microscopic eggs

from the soil

Activity: Draw A Roundworm Draw, label, and color this diagram of a roundworm in your guided notes.

Compare it to a cnidarian which we just learned about.

New Guinea Worm: Life Cycle

http://www.dhpe.org/infect/guinea.html

New Guinea Worm Emerging

Video Clip

Worms have many unique characteristics different from sponges and cnidarians.

Watch this clip: “Three Phyla of Worms_5min

45 sec”

Listen for the characteristics that worms were the first to have!

Segmented Worms

Characteristics Annelida is Latin for “Little Rings” Body is made of many segments

An earthworm has more than 100 segments! Organs are found within the segments

Segmented Worms: Closed Circulatory System

Closed Circulatory System Blood moves within a confined set of blood

vessels Five hearts are located in segments 5-13

Segemented Worms: Earthworms

How they live They tunnel for a living They are scavengers eating

dead plant and animal remains

They crawl by using stiff bristles (setae) to pull themselves along

Segmented Worms: Earthworms

Earthworms and Soil Earthworms make soil more fertile Their tunnels help loosen the soil and allow air,

water, and plant roots to move through it.

Activity: Draw a Segmented Worm

Draw, color, and label this diagram of a segmented worm in your guided notes.

Gizzard

Crop

Digestive Tract (System) starts in MouthPharynx - throatEsophagus – connects throat to cropCrop – storageGizzard – grindsIntestine – absorbs nutrientsAnus

Pharynx

Esophagus

(setae)

Color Key for Organ Systems Digestive SystemCirculatory SystemNervous SystemReproductive SystemExcretory System

Leeches are Segmented Worms

NOVA Clip_ Leeches_11min!Leeches can be very helpful worms!Fill out your Ticket Slip as you are viewing.