Coulter WORMS CHARACTERISTICS OF WORMS Biologists classify worms
Coulter WORMS
CHARACTERISTICS OF WORMS � Biologists classify worms into three major phyla: � flatworms, belong to the phyla Platyhelminthes (plat ee hel minth eez) � Roundworms, belong to the phyla Nematoda � Segmented worms, belong to the phyla Annelida
BODY STRUCTURE � All worms are invertebrates � Long narrow bodies without legs � They all have tissue, organs, and body system
NERVOUS SYSTEM � Worms are the simplest organism with a brain. � Because its brain and other sense organs are located in its head, it can detect objects, food, mates, and predators quickly. � Sense organs are sensitive to light, touch and vibrations pick up information from the environment.
FLATWORMS � Flatworms are flat and as soft as jelly. � Many flat worms are parasites. Parasite is an organism that lives inside or on another organism. � Parasites take their food from the host. Host is an organism in or on which a parasite lives. � Parasites may injure their host but rarely kill the host. � Some flatworms are free living, does not live in or on other organisms.
PLANARIANS � Free-living flatworms. � They are scavengers (they feed on dead or decaying material). � They are also predators and will attack an animal that is smaller. � Feeds like a vacuum cleaner. � Planarians glide onto their food, insert a feed tube, inject the prey with digestive juices, then suck up the digested portion.
TAPEWORM � Parasitic flatworm � Can get 10 to 12 meters long � Tapeworms absorb food from the hosts digestive system. � Some tapeworms can live in human hosts. � Many tapeworms can live in more than one host in its lifetime.
ROUNDWORMS � Roundworms have a digestive system that is like a tube, open at both ends. � A one-way digestive system is efficient. Its like a conveyer belt; start where food enters, nutrients are absorbed, then remaining is wasted. � This type of digestive system enables animal’s body to absorb a large amount of food.
SEGMENTED WORMS � Earthworms and other segmented worms have bodies made up of many linked sections called segments. � On the inside each segment has organs. For example each segment has tubes that remove waste. � Some organs are only found in certain segments. � All segmented worms have a nerve cord and digestive tube that runs the length of the body. � They have a one way digestive system.
SEGMENTED WORMS � Circulatory system is closed. � Much like the human body the blood moves in a closed circulatory system.
EARTHWORMS IN THE ENVIRONMENT � Earthworms tunnel for a living. � During rainy days they come up out of the ground to get leaves and other decaying matter that they will bring under ground and eat. � Earthworms obtain oxygen through moisture on its skin. � Earthworms help the soil in which plants grow. They burrow tunnels which allow air, water and plant roots to move through it.
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