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Phylum Annelida

By Levi Clancy for Student Reader on

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AnnelidaClitellataSubclass HirudinaeLeeches

Habitat: (Freshwater)

European medicinal blood-sucking leech. Typically ectoparasites on vertebrates and invertebrates. Feed on blood of host. Attach to host by anterior and posterior suckers. Leeches differ from other annelids by greatly reduces body cavity and loss of parapodia/setae.

AnnelidaClitellataSubclass OligochaetaOrder Lumbriculida

(Freshwater oligochaetes) Habitat: Live in sediment and silt at bottom of ponds (Freshwater).

4 pairs of setae per segment. Transparent body. Feeds on detritus. Supposedly more cooperative for studying locomotion, circulation, and behavior than planaria or dugesia.

AnnelidaPolychaetaFamily AmphitecnidaePectinaria

(Ice cream cone worms) Habitat: Inhabiting a straight, conical tube of cemented sand grains, small end projecting just above surface of substratum, very low intertidal zone in bays to outer continental shelf on open coast (marine)

Construct conical tubes with pointy end up. Head with heavy, forward-directed, stout setae used as operculum and for digging. Tubes constructed of sand grains. Head-down deposit feeders.

Order Haplotaxida

(Earthworm; "Nightcrawler") Habitat: Live in moist sediments (terrestrial)

Setal bundles usually with 2 or more setae, rarely absent. Setae often hair-like or otherwise modified (lacking parapodia). Move up to sediment surface at night anf down during the day. Also come to sediment surface in rain (one hypothesis is that it is an adaptation to find mates, both sexes end up in same place on sediment surface, as opposed to being distributed throughout sediment column).

AnnelidaPolychaetaOnuphidaeLive example collected locally: Diopatra (ornate tube worm). Elongated with proboscis armature of at least 2 pieces.. Have eyes and antennae. Usually live in parchment-like tubes (typically covered with shell pieces, algae, sticks, and other debris) up to 20cm long. Predators or scavengers; use hood shaped tube as lair, detect prey using chemo-receptors.

Habitat: Burrowing in muddy san, or mud, low intertidal zone. Low intertidal of protected shores.

Live examples: Amphitrite and Thelepus. These worms inhabit permanent burrows and use ciliated feeding tentacles to deposit fine, particulate surface deposits to the mouth. They circulate a current of water through their burrows and remove 50-60% of dissolved oxygen in respiration. Mostly tube-dwellers and specialized deposit feeders. Amphitrite is a "pellet slinger"

AnnelidaPolychaetaFamily PolynoidaeLepidonotus(Scale worms) Scales on dorsal surface. Mostly shallow water marine carnivores, but some are commensal with other invertebrates (I could not discover if this genus was free-living or commensal). Large family with 600 species; may be as long as 19cm (Antarctic)
AnnelidaPolychaetaFamily MaldanidaeBamboo wormsLive example: Clymenella. Tubiculous with small prostomium fused to peristomium. No head appendages, look like bamboo. Live head-down in their tubes and subsurface deposit feed. Commensal clam and amphipod
AnnelidaPolychaetaFamily NereidaeNeanthes

Habitat: Found in secreted mucus tubes among seaweed fronds and holdfasts in mussel beds, upper to middle intertidal zone.

Live examples: Nereis and Neanthes. 4 eyes and 4 pairs of peristomial cirri. Pharynx with pair of jaws, but can be omnivores, detritivores, carnivores, or herbivores. Large crawler, usually live in tubes or burrows. Some form highly modified epitokes. Nereis virens is aa commercially important bait worm on the east coast.

AnnelidaPolychaetaFamily Serpulidae(Calcareous tube worms) Live example: Hydroides and Salmacina (fragile tube worms). Live in calcareous tubes in which they create. Elaborate, ciliated filaments project from tube opening for suspension feeding, but can be retracted rapidly if alarmed. The tropical "Christmas Tree Worm" Spirobranchus is in this family. Hydroides is a dominant "fouling organism" on rocks, pier pilings and hulls of ships.

Habitat: Locally abundant forming tangled masses of calcareous tubes on underside of rocks lower to mid-intertidal

Species can undergo asexual reproduction by constricting its segmented. Below constriction premature tentacles form at site of pygidium. Tubes being actively secreted may increase in length from 5-25mm in 8 days.

AnnelidaPolychaetaFamily SabellidaeEudystilia

(Fan worms or Feather Duster worms) Habitat: Inhabiting a tough parchment-like tube estending deeply into protected crevices and under boulders on rocky shores. Large clumps of tubes often attracted to pilings in bays. Low intertidal to 450m (marine).

Live examples: Eudystilia and Myxicola. Tentacles form radioles used for feeding. Posterior of animal anchored at bottom of blind-ended tube or burrow. Ciliary tracts carry fecal wastes upward for expulsion.. Many produce free-standing tube elevated above substrate. In addition to sexual reproduction many routinely reproduce asexually by fission.

AnnelidaPolychaetaFamily SabellaridaePhragmatopoma

(Honeycomb worms) Habitat: Form tubes of cemented sand grains, middle intertidal zone and below on rocky shores; rarely subtidal to 75m. (Marine)

Tubiculous; tuve crafted of large (1mm) sand grains, can form massive reefs (100's of km long).. Setae of anterior segments are modified to form an operculum for closing the tube.. Suspension feeders; honeycombs distributed to take advantage of suspended food and larval supply. Larvae find a honeycomb of the same species using a chemical cue located in the cement that adults use to cement sand grains together.

Prostomiumsmall rectangular segment at the anterior end of the worm; does not contain setae; bears four small eyes and two short tentacles in Neires
Peristomiumimmediately behind the prostomium; contains the mouth on the ventral side and anterior end; does not contain setae or parapodia; bears two pairs of longer and two pairs of shorter peristomial/tentacular cirri in Neires
Pygidiumposterior segment; contains the anus as well as the tentacle like caudal cirri; growth zone between last segment and pygidium
Errantfree-living forms; slow and fast crawling; peristaltic burrowing
Setaebundles of thin transparent needle-like structures that pop out of notopodium and neuropodium; two types- simple and compound (jointed)
Parapodiaevaginated body wall; lateral pair of pedal shaped structures; paired fleshy structures extending out of the metamere; increased surface area and highly vascularized so used for gas exchange; where setae is born from or from bumps (reduced parapodia)
Epitokeerrant sexually mature being (male or female) highly specialized for swimming and reproduction; reproductive site on worm; detaches from atoke with other worms; explodes (synchronized spawning); uncommon; pelagic reproductive individuals
Atokenon reproductive individual
Caudal Cirricirri at posterior end of pygidium; tentacle-like
Notopodiumdorsal part of parapodium
Neuropodiumventral part of parapodium
Aciculumpointy dark rod that extends into the parapodium from the body wall; attached to parapodial muscle; support muscle
Simple Setaesingular unjoineted setae
Compound Setaejointed setae
Radiolescrown of tentacles; palps make spiral crown of pinnate processes; feeding apperatus
TubificidFamily Tubificidae; includes dark reddish or brownish tube-dwelling worms that dominate the deeper waters of various freshwater habitats; indicators of pollution; prefer waters with low O2 levels; live head down in tubes with posterior end out in water; setae in 4 bundles per segment
Male Genital Porepores are inconspicuous, but location is revealed by distinct swelling on the metamere; in leeches, hard to find
Female Genital Poreimmediately anterior on the 14th metamere in the same position; tiny, not surrounded by swollen lips; in leeches, hard to find
Anterior Suckeron leeches, contains mouth in center; used for inchworm movement
Posterior Suckerincludes last 6-8 body segments; anus opens on mid-dorsal surface just ahead of the posterior sucker; used for inchworm movement
Clitellumproduces mucus used during copulation and the cocoon into which the eggs are laid; secretes mucus for copulation, secretes cocoon and picks up eggs and sperm, external fertilization, direct development; travels to anterior picking up sperm and then eggs; in leeches, internal fertilization, where the eggs are
Proboscisin leeches
Cropwhere they store food ready to be ground in the gizzard (oligochaetes); organ that stores the blood/body fluids ingested, gastric caeca branch off it (leeches); lead into intestine
Gastric (crop) Caecain leeches, digestive tract branches from it; between gastric caecae are testes and ovaries