Phylum Annelida

Spirobranchus giganteus Christmas tree worm Phylum Annelida Ancestral Traits Coelomate Lophotrochozoan Protostome Closed circulatory system Cephalization Derived Traits Segmentation Metamerism Septa Setae Bristles Myelinated neurons Spirobranchus giganteus Christmas tree worm Fig. 17.2a ~ 40K species of annelids

Annelid Taxomony Class Polychaeta (many bristles) most numerous # species marine Hermodice crunculata Fig. 17.9

Annelid Taxomony Class Polychaeta Class Oligochaeta (few bristles) Freshwater, marine & terrestrial Lumbricus terrestris Fig. 17.9

Annelid Taxomony Class Polychaeta Class Oligochaeta Class Hirudinea Fixed # segments (34) Setae absent Hirudo medicinalis Fig. 17.9

Annelid Phylogeny Fig. 17.22

Annelid Body Plan Setae Fig. 17.1

Class Polychaeta Highly specialized head regions Antennae Sensory palps Feeding appendages Paired extensions of body (parapodia) Often tube-dwelling Burrow into substrate and secrete mucus Bispira bunnea sabellid worm Fig. 17.2b

Polychaete Anatomy Fig. 17.3

Polychaete Anatomy (cross section) Fig. 17.3d

Polychaeta Amphitrite Fig. 17.4

Lugworm (Arenicola sp) Polychaeta Lugworm (Arenicola sp) Fig. 17.5

Polychaeta Fig. 17.10

Polychaeta Fig. 17.11

Clade Siboglinidae (Phylum Pogonophora) Riftia pachyptila Ridgea sp Fig. 21.7

Giant tube worms (Vestimentifera) trophosome Riftia pachyptila

Polychaete Reproduction Dioecious Trochophore larvae Some species develop specialized segments containing gametes Epitokes Segments are released and gametes burst out

Class Oligochaeta Fig. 17.12b

Oligochaete Anatomy Fig. 17.12a

Oligochaete Anatomy Fig. 17.12c

Seta: a.k.a. Bristles Fig. 17.13

Oligochaete Excretory System Fig. 17.14

Oligochaete Nervous System Fig. 17.15

Oligochaete Nerve Cord Fig. 17.16

Oligochaete Reproduction Fig. 17.Fig. 17

Oligochaete Development For terrestrial oligochaetes, development is direct without any larval forms Some aquatic oligochaetes retain a trochophore-like larval stage

Common Terrestrial Oligocheates: Earthworms Octagonal-tail worm (Dendrobaena octaedra) Red marsh worm (Lumbricus rubellus) Dew-worm or nightcrawler (Lumbricus terrestris) Pink soil worm (Aporrectodea rosea) Canadian worm (Aporrectodea tuberculata) Pasture worm (Aporrectodea turgida) Woodland white worm (Octolasion tyrtaeum) Redworm (Eisenia fetida )

Quick and Easy Earthworm Morphology Guide Number & location of GTs and TPs, location & shape of clitellum Ecology Location of burrows Aporrectodea turgida Lumbricus rubellus

Aquatic Oligocheates Fig. 17.18

Class Hirudinea Fig. 17.20

Hirudo medicinalis Fig. 17.21

Phylum Sipuncula ~250 species Trochophore larvae Fig. 21.1

Sipunculan Internal Structures Fig. 21.2

Phylum Echiura ~140 species Closed circulatory system Trochophore larvae Echiurus sp Fig. 21.3

Phylum Echiura Bonellia viridis Fig. 21.4

Echiuran Anatomy Fig. 21.5

Oddities Sex determination & dimorphism in echiurans