Annelida Lab

Earthworm Anatomy

File:Earthworm head.svg

“Earthworm Head” By KDS4444 Under  Creative Commons Attribution-Share Alike 4.0 International



“Nereis” By Mark Blaxter Under public domain

Leeches Anatomy

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“Leeches” By CNX OpenStax Under  Creative Commons Attribution 4.0 International

Casts of Annelid Burrows

File:Polydora ciliata burrows.JPG

“Polydora ciliata burrows” By Rosser1954 Under Creative Commons Attribution-Share Alike 3.0 Unported


  • metamerism- Having a linear series of body segments.
  • septa- A wall dividing a cavity or structure.
  • hydrostatic skeleton- A structure consisting of a fluid filled cavity and a coelom surrounded by muscles.
  • closed circulatory system- The blood is closed at all times within vessels.
  • dorsal, ventral, lateral vessels- The dorsal ventral is closed at the posterior and open at the anterior. The ventral blood vessel runs along the lower length of earthworms.
  • metanephridia- A type of excretory gland.
  • nephrostome- The funnel-like component of a metanephridia.
  • nephridiopore- The external opening of a nephridium.
  • prostomium- The first body segment at the anterior end of a worms body.
  • peristomium- The second body segment at the anterior end of a worms body.
  • tentacles-  A flexible appendage around the mouth of an invertebrate that is used for grasping, moving , or bearing sense organs.
  • palps- One of a pair of elongated, often segmented appendages usually found near the mouth
  • mouth- It can also act as an anus for some invertebrates.
  • proboscis– Tubular mouthparts for feeding and sucking.
  • parapodia- Any of the paired unjointed lateral appendages of polychaete worm
  • acicula- They are the chitinous support rods within parapodia found in the class Polychaeta,
  • setae (chaetae)- A stiff hairlike structure found on invertebrates.
  • errant- They travel and move around.
  • sedentary- Stays in the same place for an extended period of time.
  • tube dwellers- Tube anemones live inside tubes, which are composed of a fibrous material made from secreted mucus and threads of nematocysts.
  • suspension feeding- An animal that eats material that is suspended in the water.
  • deposit feeding- An animal that feeds on on small specks of organic matter that have drifted down through the water and settled on the bottom.
  • atoke- The anterior sexless part of certain polychaete worms from which grows the sexual portion
  • epitoke  (epitoky, epitokous)- These are pelagic morphs capable of sexual reproduction.
  • clitellum- A raised band encircling the body of oligochaete worms and some leeches, made up of reproductive segments.
  • testes- The reproductive organ in males.
  • ovary- The female reproductive organ where eggs are produced.
  • seminal receptacle (spermatheca)- The storage organ for male gametes inside the female.
  • seminal vesicle- Each of a pair of glands that open into the vas deferens near its junction with the urethra and secrete many of the components of semen.
  • annelid digestive system- This consists of an unsegmented gut that runs through the middle of the body from the mouth, located on the underside of the head, to the anus, which is on the pygidium. The gut is separated from the body wall by the body cavity, called the coelom.
  • pharynx- Part of the digestive system.
  • esophagus- Connects the throat to the stomach.
  • crop- Where the food is stored.
  • gizzard- Where the food is ground up.
  • intestine- Where food is digested and nutrients are absorbed.
  • typhlosole- An internal fold of the intestine or intestine inner wall.
  • cerebral ganglia- Where the nerve cord originates.
  • subpharyngeal ganglia- The most anterior and the most prominent ganglion.
  • nerve ring- A ring around the pharynx that consists of a pair of ganglia.
  • ventral nerve cord- The nerve cord that runs from the anterior to the posterior.
  • leeches- anterior, posterior suckers- Anterior and posterior suckers are used to connect to a host for feeding.