Download Other Deuterostomes

Other Deuterostomes
Aside from lophophorates,
echinoderms etc.
= three other phyla of
Deuterostomes
Characteristics?
Phylum Chaetognatha
arrow worms
Chaetognath Phylogeny
Harzsch & Mueller, 2007
Chaetognath Characteristics
Small phylum ( 120 species), 2-120mm, small fast active
swimmers, main zooplankton predators = copepods (most
planktonic, 3 species benthic), indicators for fisheries,
Transparent (some white, some carotenoid pigmentation)
Chaetognath Bauplan
Streamlined =
virtually perfect
bilateral
Trimeric body =
head, trunk, tail
Paired
lateral/single tail
fin
Grasping spines
(hooks), small
spines (teeth)
Corona ciliata
Hydrostatic
skeleton
Chaetognath Physiology
Carnivores, particularly
copepods
Spines/teeth bear poison
No special organs for
excretion/circulatiom etc.
NS = cerebral, ventral,
connectives (paired)
Corona ciliata, ocelli
Locomotion through
longitudinal muscles (fins =
stabilizers)
Chaetognath Reproduction
Hermaphrodictic
Paired ovaries =
Trunk
Testes = tail
Sperm
maintained
outside testes
Fertilization
external
Some with
marsupial
pouches
Radial cleavage
Direct
development
Phylum Hemichordata
aka the acorn worms
Hemichordate Phylogeny
Hemichordate External Bauplan
Tripartite =
Proboscis,
collar, trunk
Proboscis =
short, conical
Proboscis stalk
Branchial
trunk = gills
Genital trunk
= genital pores
& wings
Hepatic region
= color change
Hemichordate Internal Bauplan
Simple digestive tract with
associated hepatic system
Heart in proboscis, closed
circulation
Glomerulus = excretory
= heart/kidney complex
Protocoel = limited coelom
Hemichordate Feeding
Living in tubules in
soft sediment = Ushaped tubes
Detritus/live plankton
Mucous secretion =
over proboscis & collar
Move to mouth by
pre-oral ciliary organ
Hemichordate
Reproduction
Asexual reproduction =
fragmentation
Gonochoristic, no sexual
differentiation
Paired sacular gonads in
trunk
Free spawners = mucoid egg
masses
! Coating breaks in
seawater
Some species brood
Tornaria larva = bipinnaria
larva