Ecdysozoa protostomes {annelid}| are higher worms.
skin
Epidermis secretes mucus and cuticle, to prevent water loss.
movement
Circular and longitudinal muscles cause movement by stretching and contracting.
digestion
Annelids have schizocoelom. Annelids have mouth, pharynx, esophagus, crop, gizzard, and straight intestine.
blood
The two main blood vessels connect by pairs of muscular tubes acting like hearts. Vessels have capillaries.
nervous system
Head has stimulating ganglion and inhibiting ganglion. Segments have one small ganglion each. Reflex arcs run from sense cells to muscle sets. Neurons have few dendrites, no myelination, few Schwann cells, no oligodendroglia, no astrocytes, no microglia, no nerve tracts, no inhibitory surrounds in receptor fields, no feedback circuits in receptor fields, and no amacrine cells in receptor fields. Neurons have basic neurotransmitters, ion channels, excitability, synaptic potentials, pacemakers, and rhythmic voltage patterns, with frequency twice as high as in vertebrates.
senses
Annelids can have eyes and antenna. Membranes cover visual pits to protect photoreceptor cells.
pigment
Earthworms have pigmented skin cells.
pain
Worms feel no pain.
Segments have two strong short hairs {bristle, hair}| on epidermis.
Annelids have 100 similar parts {segment, worm} {segmentation, worm}|, with pairs separated by septa.
Walls {septum, segments} separate annelid segment pairs.
In septa, blood vessels surround ciliated-funnel pairs {nephridium}. Tubes lead from nephridia to surface to carry away wastes.
Tubes from nephridia have enlargements {bladder, annelid}| in centers.
Annelid stomachs have one storage part {crop, stomach}| and one gizzard.
Annelid stomachs have one crop and one digesting part {gizzard}|.
Testes and ovaries are in same animal {hermaphrodite}| and have tubes leading to surface. Two worms press together and deposit sperm in each other.
Worms form coverings {cocoon}| from bottom to head, in which they first deposit eggs and then sperm.
Annelids {earthworm} {oligochaeta} {night crawler} {worm, animal} can have few bristles and live in soil and fresh water.
Annelids {leech} (Hirudinia) can have suckers at ends to draw blood from vertebrates, use anticoagulant, and have no bristles.
Marine annelids {marine annelid} {archiannelida} can be non-segmented marine worms without bristles.
Ocean annelids {ocean annelid} {polychaeta} {polychaetes} can have many bristles and separate sexes, which release gametes into water by seasonal, lunar, and diurnal cycles.
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Date Modified: 2022.0225