### animal | worm:

Polychaete
* Many polychaetes are filter feeders, others are deposit feeders or active predators
  - burrow into the ocean floor for protection
  - crawl on the bottom, hiding under rocks or coral
* Most polychaetes achieve density
  - also have gills to aid in respiration
  - are small and short-lived with a high secondary production
* Most polychaetes become active swimmers
* Most polychaetes have a closed circulatory system
  - separate sexes, rather than being hermaphrodite
  - tentacles
  - inhabit fresh water
* Most polychaetes live in habitats
  - oceans
* Some polychaetes belong to families
  - build tubes
  - extend proboscises
* Some polychaetes harbor bacteria
  - symbiotic bacteria
* Some polychaetes have active lifestyle
  - jaws
  - larvae
  - mechanisms
  - mouthparts
  - organs
  - permanent organs
  - sex organs
  - structures
  - various mechanisms
* Some polychaetes live in black sea
  - burrows
  - estuaries
  - permanent burrows
  - tubes, others are active and crawl or swim around
  - on the external surface of such inver- tebrates as sea stars and sea urchins
  - reproduce by budding
  - show distribution
  - take care
* also differ from other annelids in that they have antennae and specialized mouth parts.
* are a taxanomic class of segmented worms
  - also successful at other lifestyles
  - among the most common animals in shore line environments
  - an abundant group found in prac- tically every habitat in the ocean
  - common annelids that live in fresh and salt water
  - critical members of all ocean food webs
  - dominant benthic fauna in the marine environment
  - mostly marine
  - part of the diets of shrimps, crabs, a variety of fishes, and even some shore birds
  - particularly common on and in muddy and sandy shores
* are the most diverse and abundant of the worm groups
  - group of deposit feeders in the soft sediments of the shelf
  - very useful organisms for monitoring the marine environment
* burrow in sediments or live in tubes.
* exhibit a wide range of lifestyles.
* have a complex pharynx which they are able to evert to catch their prey
  - pair of flaps, called parapodia, on each segment
  - considerable powers of regeneration
* have separate sexes and fertilization is external
  - sexes, and rely on external fertilization in water
  - well-developed blood vascular systems
* includes brains
  - cell membranes
  - corpi
  - cytoplasm
  - ears
  - heads
  - nuclei
  - plasma membranes
  - sections
  - skulls
  - vacuoles
* incorporate pellets into dwelling tubes.
* often live commensally with sponges, mollusks, echinoderms, and crustaceans.
* play a variety of roles in coral reef ecosystems
  - an important role in marine food chains
* represent the largest class of annelids and are predominantly marine.
* tend to synchronise spawning to maximise the odds of fertilisation.

### animal | worm | polychaete:

Sedentary polychaete
* Some sedentary polychaetes live in burrows.
* spend most of their time in tubes or permanent burrows.

Ribbon worm
* All ribbon worms are predators that feed on worms and crustaceans.
* Most ribbon worms possess receptors.
* Some ribbon worms possess cord
  - nerve cord
* are incredibly elastic.
* feed on small animals and algae.
* have a distinctive eversible proboscis stored in a rhynchocoel.

Round worm
* Many round worms are saprotrophic and actively break down organic material, such as leaf-litter.
* Most round worms are free-living bust some are parasitic.
* Most round worms live in habitats
  - ocean habitats
* Some round worms are parasites of crustaceans, insects and even other water worms.
* Some round worms kill insects
  - moose
* are difficult to avoid in puppies
  - often quite parasitic