Zool 110 Lec: Annelids and Ecdysozoans (

phylum onychophora and phylum tardigrada

what are the two phyla within the group ecdysozoans

Phylum Annelida

cephalized vermiform animals with segmented (metameric body plan), triploblastic, coelomate lophotrochozoans, coelom usually divided by septa, marine/freshwater/terrestrial/most free-living/some symbionts or ectoparasites, transparent cuticle secreted by epithelial tissue

Phylum Annelida reproduction

fission and fragmentation, monoecious sexual reproduction with trochophore larva or direct development

polychaetes are what kind of group

3 multiple choice options

Errantia and Sedentaria

what are the two major clades in Annelida

Clades of Phylum Annelida phylogenetic breakdown

Clade Errantia (Phylum Annelida)

motile polychaete worms, many are euryhaline, well differentiated head with sense organs, parapodia (paired appendages) on each segment, many setae arranged in bundles on parapodia, no citellum

setae

Bristle-like structures that help segmented worms move

Clade Errantia body plan

prostomium = mouth, sometimes retractable, pharynx that can be everted, parapodia with setae

parapodia

Paddlelike appendages that assist aquatic annelids in locomotion

Clade Errantia Reproduction

no separate sex organs, usually dioecious, external fertilization

Clade Errantia Sexual Reproduction

epitoke = segments packed with gametes that detach from the atoke and rise to the surface

Clade Errantia Asexual Reproduction

epitokes = complete worms that are budded of posterior end of atoke

Clade Sedentaria

tubeworms, live in parchment tube

Amphitrite (terbellid) "spaghetti worm"

part of clade sedentara, tentacles extend across sand and sweep up food

Echiurids (spoon worms)

part of clade sedentaria, proboscis with gutter

Echiuridae and Clitella

what are the two subgroups of clade Sedentaria

Subgroup Clitella (Clade Sedentaria)

have a clitellum, freshwater and terrestrial, oligochaetes (non-monophyletic group), class Hirudinia

Subgroup Clitella body plan (e.g. oligochaete)

Oligochaete (subgroup clitella) excretory and nervous system

paired nephridia in each segment, cerebral ganglia (brain) above pharynx, connectives (nerves) pass around pharynx to connect brain to first pair of ganglia

Oligochaete (subgroup clitella) reproduction

clitellum picks up eggs and sperm and fertilizes them and then it pops off and acts as a cocoon where the new worms eventually emerge from

Class Hirudinida (Clade Sedentaria Subgroup Clitella)

order Hirudinea (true leeches), no setae, anterior and posterior suckers, carnivorous on small invertebrates, temporary parasites or permanent parasites, fluid feeding = salivary glands secrete anesthetic cand anticoagulants

Class Hirudinida body plan (Clade Sedentaria Subgroup Clitella

hermaphroditic with clitellum only during breeding season

Group Spinuncula

spinunculans (peanut worms), introvert = proboscis

Clade Ecdysozoa

protostomes with a cuticle that is shed (molted) through ecdysis

Phylum Onychophora

velvet worms, 70 species of small caterpillar like animals, terrestrial, open circulatory system, tracheal respiratory system, slime glands for hunting

Phylum Tardigrada

water bears, 900 species, mostly terrestrial in water film around mosses and lichens, some freshwater or marine

Phylum Tardigrada body plan

elongated, unsegmented body, with stubby unjointed legs each with 4-8 claws, large brain, malpighian tubule excretory system, open circulatory system, use sharp stylet in pharynx to feed

Phylum Tardigrada reproduction

dioecious, many parthenogenetic, egg-laying occurs at molting