### animal | worm:

Acanthocephalan
* Most acanthocephalans parasitize fishes.
* are absent or accidental components in the helminth fauna of elasmobranchs
  - dioecious
* have no gut and absorb nutrients directly from the host 's gut.

Adult worm
* live in hosts.
* matures in the capillaries creating inflammation.

Angleworm
* includes brains
  - cell membranes
  - cells
  - corpi
  - cytoplasm
  - ears
  - faces
  - heads
  - nuclei
  - plasma membranes
  - sections
  - skulls
  - vacuoles
* synonym of earthworm.

### animal | worm:

Annelid
* Many annelids are capable of regeneration.
* Most annelids possess short external bristles called setae, or chaetae, composed of chitin.
* Some annelids are protandric hermaphrodites, in which the sexual stages alternate
  - live in the ocean.
  * are made of one or more body segments. Each segment has one or more rings. Annelids reproduce sexually by hermaphroditic cross-fertilization. They can regenerate cut off pieces of their body. Unlike sponges, which can come back together if ripped apart. They have a hydrostatic skeleton, a one-way digestion system, and bilateral symmetry
* acquire food in ways specific to their diets which vary widely.
* also exchange gases by diffusion.
* are coelomate animals meaning they have a true coelom within their body
  - found throughout the world, from deep ocean bottoms to high mountain glaciers
  - hermaphroditic but cross-fertilize during sexual reproduction
  - segmented both externally and internally
* are the most efficient animals of worm body plan
  - simplest group of true coelomates
  - worms
* have a body that is made up of repeating segments
  - closed circulatory system
  - complete digestive tract and circulatory system
  - cylindrical body with distinct segements
  - more complex system for excretion
  - mucus covering, segmented bodies, sometimes bristles and openings
  - an open circulatory system
* have bodies composed of a series of fused rings
  - that are segmented
  - both longitudinal and circular muscles, so better control over their movement
* have no jointed legs and arthropods do
  - lungs, although many species have simple gills
  - some of the fastest reflexes in the animal kingdom
  - two sets of muscles that are used to contract and elongate the body
  - very well-developed internal organs
* live in the sea, most freshwater habitats, and damp soil.
* thus meet the chain requirement by creating a hierarchy of organs.

Annelid worm
* Most annelid worms feed on nutrients
  - soil nutrients
* Some annelid worms live at bottoms
  - serve as hosts
* are excellent examples of a hydrostatic skeleton in the form of a coelom in action.
* have a nervous system.
+ Annelid, Nervous system
  * Annelid worms have a nervous system. Rouse G. 1998. The Annelida and their close relatives, in Anderson D.T. 'Invertebrate Zoology'. Oxford University Press.

Aquatic worm
* have a life span between several weeks to years.
* live in lakes, ponds, streams, and wetlands.
* move by stretching and pulling their bodies along.
* reproduce sexually or by dividing their bodies.

Arrow worm
* Most arrow worms possess heads.
* are hermaphroditic, but cross- fertilization is the rule
  - important predators using their bristle like jaws to catch their prey
  - voracious predators, with curved bristles that act as powerful jaws
* consume an assortment of other prey when it is available.
* have neither vascular nor excretory systems.

Arterial worm
* live in the arteries of white-tailed deer.
* pose no threat to humans, and the venison of infected deer is safe for consumption.