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Blackworm fACTS

Blackworm fACTS. Classification. Lumbriculus variegatus. Description. Posterior Anterior. Require Nutrients . Fresh water invertebrate that feeds on decaying vegetation and microorganisms . Reproduction.

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Blackworm fACTS

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  1. BlackwormfACTS

  2. Classification Lumbriculus variegatus

  3. Description Posterior Anterior

  4. Require Nutrients Fresh water invertebrate that feeds on decaying vegetation and microorganisms Reproduction Hermaphroditic – contain both maleandfemale sex organs [like earthworm] 1. Sexual - Sperm exchanged > produce cocoons containing 4-11 fertilized eggs   After 2 weeks > new worm emerges about 1 cm in length- not common 2. Asexual- regeneration - can be divided into smaller pieces and form new worm

  5. Cellular Respiration Occurs in tail> forms right angle at water surface > gas exchange occurs between outside air and pulsating blood vessel Nervous System Nerve Cord_-runs entire length of body- located beneath intestines PN, prostomial nerves; CG, cerebral ganglion; n1-n4, segmental nerves 1-4; VNC, ventral nerve cord. Movement Muscles- 2 Layers Line Body- provide movement - controlled by Nerve Cord Circular- around body Longitudinal- length of body

  6. - Together cause constricting and lengthening followed by increasing • diameter and shortening • allow worm to move in corkscrew fashion in water, swimming short • distancesor crawl through soil 2. Chaetae- 2 pairs of bristles located on each segment - used to anchor worm and increase traction - help worm crawl Digestion/Excretion • has complete digestive tract • including mouth and anus

  7. Circulation System - consists of dorsal, ventral and lateral vessels Contracting muscles around posterior vessel form waves “like opening and closing fist” and move blood from posterior end toward anterior end Blood flow Starts at posterior end “pulses” through dorsal vessel toward anterior end Returns to tail through ventral vessel no “pulsing” Lateral vessels supply blood to segments Types of Circulatory Systems- 1. Closed- blood moves through body in vessels [arteries/veins] 2. Open-blood not contained in vessels, blood bathes all internal organs BLACKWORMS HAVE A CLOSED CIRCULATORY SYSTEM

  8. Respond to Environment Protective Response When at surface of water, tail of worm can detect shadow [ using photoreceptors ] or sudden vibration Rapid Reflex- responds by quickly contracting its muscles, withdrawing tail from predator When anterior end is touched, it will change direction of movement When posterior end is touched, moves forward very quickly

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