WORM NOTES Chapter 9, section 4

Are grouped into

Body Structure: Invertebrates Long narrow bodies with no legs Tissue, organs and body systems Bilateral symmetry Have head and tail ends

b. Nervous system i. Simplest organisms with a brain sensory organs in its head end to respond to vibrations, food, mates, and predators

c. Reproduction i. sexually AND asexually ii. Some worms are hermaphrodites - (both male and female)

Characteristics of Flatworms: Duh, flat bodies Examples include tapeworms and planarians

Parasites Lives inside another organism and takes its food from that organism example: Tapeworms

Hosts Organism that a parasite lives on or in

Does a parasite effect its host? It sure does… Abdominal pain, anorexia, weight loss, – USUALLY asymptomatic! Problems arise when the tapeworm becomes too large and starts blocking the bowel or robbing us of vital nutrients Tapeworm cysts can take up valuable space. If the cyst settles in the brain, eye or liver, normal function of these organs may be severely restricted.

Free-living organisms Organisms that don’t live in or on other organisms

Free-living flatworms live: Live in ponds Damp soil Oceans

Characteristics of Planarians Phylum Platyhelminthes  “platy” means flat Eyespots – to detect light Long feeding tubes that come out of their “stomach” area Scavengers Predators – meat eaters Live in cold ponds and streams

How Planarians eat! Extends feeding tube (pharynx) into food source Releases digestive juices to break it down Sucks food in Undigested food exits through feeding tube (pharynx) A planarian eating a midge.

What about their eyesight? They have eyespots only for detecting light. Find food by other sensing organs in their head area (no need to write this info down)

How Planarians reproduce Sexually with eggs and sperm Asexually by regeneration (growing body pieces back)  You can cut the head off and it will grow back

Tapeworms: Adult Tapeworm – each segment contains eggs and sperm. When fertilized they break off and are released with wastes (you know, poop).

Tapeworms Body adapted to absorbing already digested food  Have a head (Scolex) with hooks and suckers  No mouth or stomach – no eyes either hooks

Lifecycle of dog tapeworm: Dog eats rabbit infected with tapeworm larvae It attaches to the lining of the dog’s digestive system. The attached tapeworm grows and produces eggs/sperm. Fertilized eggs leave the body with wastes.

Lifecycle, continued: A rabbit (or sheep or whatever) eats grass covered with the fertilized eggs and becomes infected with tapeworm larvae. Then it starts over…

ROUNDWORMS a. General Characteristics Belong to the phylum Nematoda tiny and hard to see but may be most abundant animals on earth

Body Structure cylindrical bodies pointed at each end digestive system that is like a tube open at both ends  food travels in one direction from mouth to anus  more efficient  allows animal’s body to absorb a large amount of needed substances in foods.

Types of roundworms Ascaris Hookworms Trichinella Heartworms

Roundworms, Continued EXAMPLE: Heartworm in your pet

Parasite examples

Examples of heartworms

Segmented Worms

Body Structure body divided into segments  outside segments look almost identical  inside there are many differences  Many organs repeat themselves *each segment has tubes to remove wastes

More about body structure Reproductive organs in certain sections only Nerve cord & Digestive system that runs length of worm’s body two openings – mouth and anus

Circulatory System Closed circulatory system  This is faster than an open circulatory system (moves blood more quickly) 5 pairs of hearts Dorsal blood vessel – along back Ventral blood vessel – along belly

Earthworms and the Environment need moist soil because oxygen is obtained through moisture on it’s skin helpful to the environment  loosen soil by tunneling allowing air, water, and plant roots to move through it  make soil more fertile by their droppings

What you will see inside:

Bring your notes to class when we dissect!!! Please note diagrams on page 3; they will be very helpful!!!

V.Questions to see if you understand worms a: Nematodes are more complex than flatworms because… They have a mouth and an anus! Makes it more efficient. Wow is that complex!

b. What is the difference in complexity between the digestive systems of a flatworm and a roundworm? Flatworm is 2-way, roundworm is 1-way since it has 2 openings

Change last question… What are the phylum names for each? Flatworms: Roundworms: Segmented worms:

ANSWERS: Flatworms: Platyhelminthes Roundworms: Nematoda Segmented worms: Annelida

Circle the letter of each sentence that is true about roundworms C. Most roundworms are tiny and hard to see D. Roundworms have a digestive system that is like a tube, open at both ends

Wastes exit a roundworm’s digestive system through an opening called the… anus

What is the advantage of a one way digestive system? Faster or more efficient

Circle the letter of each sentence that is true about segmented worms B. Earthworms are a type of segmented worm C. Segmented worms have bodies made up of many linked sections

Earthworms have a digestive system with ____ openings. 2

What is the advantage of a closed circulatory system? Blood moves faster

Circle the letter of each characteristic of earthworms. B. Make tunnels C. Get oxygen through the skin

How do earthworms improve the soil? Tunnels allow air, water, and plant roots to move through Makes soil more fertile from wastes