Polyzoa and Kryptozoa
Chapter 15
Lophophores
• Phylogenetic
evidence indicates
that lophophores
evolved more than
once.
• Lophophores have a

crown of ciliated
tentacles that are used
in food capture and
respiration.
• Thin ciliated walls act
as respiratory surface
for gas exchange.
Lophophores
normally extended but can be withdrawn
for protection.
Lophophores
 Three major phyla were previously lumped
under lophophores: Phoronida, Ectoprocta,
Brachiopoda.
 Lophophores and animals with trochophore larvae
features are merged to form a new group called
Lophotrochozoans.
 Ectoprocta is now placed in a clade called Polyzoa
with Cycliophora and Entoprocta where all three taxa
share ciliated tentacles.
 Brachipoda and Phoronida are placed in the clade
Brachiozoa.
Clade Polyzoa
• Phylogenetic studies using multiple genes have
supported the clade Polyzoa that unites the
cycliophorans, entoprocts and ectoprocts.
• Members of the three groups have fascinating body
plans and life cycles.
Phylum Cycliophora
• Cycliophorans live exclusively on mouthparts of
marine decapod crustaceans in northern
hemisphere.
• Attach to bristles with an adhesive disc on the end of
an acellular stalk.
Phylum Entoprocta
 About 150 species in
the phylum
Entoprocta occur
worldwide.
 Usually in marine
environments.
 Less than 5 mm long
and mostly
microscopic,
resembling hydroid
cnidarians.
Phylum Entoprocta
 Body or calyx is cup
shaped and bears a
circular crown of
ciliated tentacles.
 Tentacles on lateral
and inner surfaces
can roll inward but
cannot be retracted
into the calyx.
 Gut is U-shaped with both mouth and anus opening
within the circle of tentacles.
 Attaches by a stalk with adhesive glands.
 Modified spiral cleavage leads to trochophore-like larva.
Phylum Ectoprocta
 Phylum Ectoprocta
contains aquatic
animals that often
encrust hard
surfaces
(bryozoans).
 Approximately 4500
living species.
 Inhabit both shallow
freshwater and
marine habitats.
Phylum Ectoprocta
 Most are sessile, some slide slowly, and others crawl
actively across surfaces.
 Mostly colony builders.
 Each member is less than 0.5 mm in length and is
called a zooid.
Phylum Ectoprocta
 Ciliated tentacles are also a respiratory device
permitting gas exchange between surrounding water
and internal coelomic fluid.
 Gut is U-shaped:
 Mouth opens inside the lophophore ring, and the anus
opens outside the ring.
Phylum Ectoprocta
 Zooids feed by
extending
lophophores into
surrounding water to
collect tiny particles
 Zooids secrete
exoskeleton in which
they live in.
Phylum Ectoprocta
 Exoskeleton may be gelatinous, chitinous, or stiffened




with calcium and possibly impregnated with sand.
Shape may be boxlike, vaselike, oval, or tubular.
Some colonies form limy encrustations on seaweed,
shells, and rocks.
Others form fuzzy or shrubby growths or erect branching
colonies.
Freshwater colonies may form mosslike colonies on
stems of plants or on rocks.
Phylum Ectoprocta
 To feed, the
lophophore is
extended and
tentacles spread out
into a funnel.
 Cilia on tentacles
draw water into
funnel.
 Food particles caught
by cilia in the funnel
are drawn into the
mouth.
Phylum Ectoprocta
 Freshwater
ectoprocts undergo
budding that
produces
statoblasts.
 Hard, resistant
capsules containing a
mass of germinative
cells.
Phylum Brachiopoda
 Brachiopods appear
similar to bivalve
molluscs because they
have two calcareous
shell valves secreted by
a mantle.
 Dorsal/ventral instead
of left/right.
 Pedicel – a fleshy stalk
used for attachment.
Phylum Brachiopoda
 Brachiopods are an
ancient group they
were prolific during the
Paleozoic and
Mesozoic eras.
 One living species,
Lingula, is considered
to be a living fossil
since it has changed
little since the
Ordovician (505 mya).
Phylum Brachiopoda
 Characteristics of both protostomes &
deuterostomes:
 Cleavage is radial (deuterostome)
 Coelom formation enterocoelous at least in some
brachiopods. (deuterostome)
 The relationship of the blastopore to the mouth is
uncertain.
Phylum Phoronida
 Species in the phylum
Phoronida are small
wormlike animals.
 Secrete tubes to live in.
 Tentacles of the
lophophore are
extended for feeding.
 U-shaped digestive
tract.
Phylum Phoronida
 Characteristics of both protostomes &
deuterostomes:
 Blastopore becomes mouth (protostome).
 Cleavage is radial (deuterostome).
 Coelom formation – highly modified enterocoelous
(deuterostome).
Phylum Nemertea
 Ribbon worms,
phylum Nemertea,
use a proboscis to
capture prey.
 Almost completely
marine.
 Active predators.
 General body plan
similar to
turbellarians.
Phylum Nemertea
 An anus is present providing these worms
with a complete digestive system.
 Nermeteans are the simplest animals to have
a closed loop blood-vascular system.
Phylogeny and Diversification
 Molecular characters have changed the phylogeny of
Lophophores and its associated groups.
 Developmental characters associated with spiral
cleavage are presumed to be ancestral to the clade.
 Spirally cleaving embryos have mosaic cleavage
patterns and mesoderm formation from particular
endoderm cells.
 But many members of the Lophophores do not follow
these features and prevent clear placement into
specific clades and groups.
Phylogeny and Diversification
 Placement of Nemerteans are contentious and highly
debatable.
 Nemerteans used to be with Platyhelminthes due to
flame cells and cilated epidermis but the presence of
complete digestive tract and eversible proboscis in a
unique coelomic cavity counters this original
grouping.
 Nemerteans coelomic cavity above the digestive
tract sets them apart form other coelomate animals.