1. The “Lophophorates” Phylum Bryozoa Phylum Phoronida Phylum Brachiopoda
Once upon a time, there were 3 phyla that had an apparent
synapomorphy: the lophophore, a horseshoe-shaped ring
of ciliated tentacles surrounding mouth, used in filter feeding
Phylum Bryozoa
Phylum Phoronida
Phylum Brachiopoda
- colonies made of
microscopic zooids
- worm-like, tube-dwelling; large
- 2 shell valves; large

2. Lophophorates on the Tree of Life
Lophophorates were 1st placed in the Deuterostomes, as:
- their early embryonic cleavage is radial & indeterminate
- body forms with 3 regions and a 3-part coelom
However, they also share some Protostome characteristics:
- mouth develops from blastopore in one group, Phoronids
- larvae of some look like modified trochophores
- they can make chitin, a building material not found in
Deuterostomes
Where does molecular analysis of DNA + protein sequence data place them...?

3. OLD Annelids SCHOOL (WRONG) Arthropods Molluscs Protostomes Nematodes
Platyhelminthes
Lophophorates
Chaetognaths
Deuterostomes
Echinoderms
Chordates

4. DNA analysis: Lopho’s are protostomes
Comparison of the highly-conserved
18S rRNA gene sequence showed
that all 3 lophophorates grouped
with protostomes, not with the
deuterostomes
Proposed clade within protostomes:
the Lophotrochozoa
- lophophorates, molluscs + annelids;
excludes arthropods + nematodes
- no synapomorphy; either have a
lophophore, or a trochophore
larva (not really legit for naming)
Halanych et al. 1995

5. Protostomes Spiralia Nematodes Arthropods Deuterostomes Phoronids
Chaetognaths
Protostomes
Spiralia
Nematodes
Arthropods
Echinoderms
Chordates
Deuterostomes

6. Spiralia – spiral cleavage of embryos
Phoronids
Chaetognaths
Lophotrochozoa
Spiralia – spiral cleavage
of embryos
Nematodes
Arthropods
Ecdysozoa –
molting phyla
Echinoderms
Chordates
Deuterostomes

7. Lophotrochozoa Trochozoa phyla with a trochophore larval stage
Phoronids
Chaetognaths
Lophotrochozoa
Brachipoda
Nemertea
Mollusca
Annelida
Trochozoa
phyla with a
trochophore
larval stage
Platyhelminthes
Rotifera
Platyzoa
Bryozoans
Entoprocts
Cycliophorans
Spiralia
Polyzoa

8. The former “lophophorates” are scattered among all the major clades
Phoronids
Chaetognaths
The former
“lophophorates”
are scattered
among all the
major clades
Brachipoda
Nemertea
Mollusca
Annelida
 they are not a
monophyletic
group !!
Platyhelminthes
Rotifera
Bryozoans
Entoprocts
Cycliophorans
Spiralia

9. All recent molecular studies support this version of protostomes
Spiralia: animals with spiral cleavage of their embryos
Platyzoa: flatworms, rotifers
Polyzoa: bryozoans, entoprocts, cycliophorans
Trochozoa: animals with a trochophore stage
 annelids, molluscs, nemerteans, brachiopods
Ecdysozoa: animals with an external cuticle, that molt to grow
 nematodes, arthropods, minor phyla
Phoronids
Chaetognaths
placement uncertain;
phoronids are probably trochozoans
Note: all of these group names are names of clades, but do not
correspond to phylum, class, order ranks

10. Lophophorate characteristics
Body divided in 3 parts, each with its own coelomic space:
This 3-part body/coelom structure is typical of deuterostomes
like us... probably an ancestral feature kept by deuterostomes
and lophophorates, which changed in the Spiralians
Anterior Coelomic space Body region
Protocoel Prosome
Mesocoel Mesosome
Posterior Metacoel Metasome

11. The Lophophore 3 phyla have a lophophore, a circle of tentacles used
in suspension feeding
Ciliated growth of tentacles arising
from mesosome (middle coelomic
compartment)
- tentacles contain fingers of coelom
- surround mouth, but not anus
Is not a synapomorphy; evolved
independently 2-3 times (= homoplasy)

12. Lophophore Function
Cilia on lophophore tentacles generate a feeding current
- cilia catch particles, bounce them back and forth to mouth
- each tentacle has 1 row of frontal
cilia and 2 rows of lateral cilia

13. Phylum Bryozoa - Prosome reduced/absent; mesosome fills lophophore +
5,000 spp.
- Prosome reduced/absent; mesosome fills lophophore +
connects to metasome, which contains viscera (organs)
- Colonial, made up of individual zooids that bud asexually
zooids bilaterally symmetric, often polymorphic
U-shaped gut, anus outside lophophore
No excretory or circulatory systems; whole body of an
individual zooid may be reduced to “brown body” + excreted
- Hermaphrodites, as a colony; gonads simple, temporary
- Undergo radial cleavage (like deuterostomes);
blastopore does not become mouth or anus (unique to them)
Most produce lecithotrophic larvae that settle rapidly;
important members of fouling communities

14. Polypide = soft tissue + lophophore
Zooid = exoskeleton + polypide
Autozooids = feeding
Heterozooids = no lophophore,
do other functions for colony
Compare & contrast bryozoans
with hydrozoans (Cnidaria) –
What convergent adaptations for
colonial life do the 2 groups show?

15. Heterozooids = no lophophore,
do other functions for colony
Ovicells – incubators for developing embryos
- sperm taken up from seawater, used to fertilize eggs
- parental zooid degenerates, forming nutritive tissue
chamber for fertilized eggs
Avicularia – giant claws used to defend colony
- polypide reduced to a few large muscles
- claw is modified operculum
- prevents fouling by larvae + spores of other organisms

16. colony of inter-connected zooids swimming larva ancestrula asexual
reproduction
Colony starts as a metamorphosed larva, which grows into
one original zooid, the ancestrula
ancestrula then clones itself to form whole colony, asexually

17. Class Stenolaemata
- most extinct
- tubular, calcified exoskeleton

18. Bryozoan Groups Class Stenolaemata Class Gymnolaemata
- zooids connected by funiculus (a coelomic link)
Order Cheilostomata
- openings covered by opercula
- embryos usually brooded in ovicells
- avicularia: claws function in defense
Order Ctenostomata
- cylindrical zooids, attached by stolon
- no operculum, ovicells or avicularia

19. Class Gymnolaemata Order Ctenostomata - cylindrical zooids funiculus
- flexible, chitinous
exoskeleton
- zooids sprout from
a horizontal runner
called the stolon
(at some distance from
each other)
Funiculus = coelomic
connection between zooids
(may even link stomachs)
funiculus

20. Class Gymnolaemata Order Ctenostomata
Extend lophophore by hydrostatic pressure:
- parietal muscles contract, pressurizing coelom
- fluid extends lophophore, expands tentacles
Retract lophophore by muscle action:
- lophophore pulled in by retractor muscles
- collar folds over withdrawn tentacles
collapses over
tentacles
compare and contrast
feeding in this group
with sipunculan worms!

21. Class Gymnolaemata Order Cheilostomata - polymorphic zooids
- exoskeleton made of chitin + calcium carbonate
- non-stoloniferous growth:
walls of the zooids are attached
to each other (grow in a sheet)

22. Class Gymnolaemata Order Cheilostomata
- hard casing causes a problem: how to pressurize coelom?
- solution: flexible frontal membrane on top
- muscles pull membrane down,
pressurizing coelom
lophophore extends
In most successful group,
membrane = the ascus
- internal, for protection;
outer wall is solid
- pore lets seawater in
when ascus is pulled down

23. Schizoporella unicornis
showing orange opercula
covering zooids

24. lophophores extended Eurystomella bilabiata, only food of the
“Hopkin’s Rose”
sea slug
lophophores extended

25. Bugula
neritina
- common fouling organism, worldwide
Contains defensive compounds, the bryostatins
- made by a unique bacterial symbiont
- chemicals protect the large, lecithotrophic larvae
from predation during their brief planktonic journey
- in clinical trials as an anti-cancer drug

26. Bryozoans are sister to a clade composed of 2 phyla that
were never even grouped as “lophophorates”
Platyhelminthes
Rotifera
Platyzoa
Polyzoa
Bryozoa
Cycliophora
Entoprocta
- based on
molecular
analysis of
protein
sequences

27. Phylum Entoprocta - solitary or colonial filter feeders
150 species
- solitary or colonial filter feeders
- feed with anterior ring of ciliated tentacles, but anus opens
inside the ring (ento = within, procta = anus)
- no blood vessels, U-shaped gut
- spiral, determinate embryonic cleavage (typical protostome kind)
- some species have trochophore-like larvae
embryos + larvae are like other protostomes,
adults are like bryozoans.. close relatives
that develop quite differently

28. water moves through the ring of ciliated tentacles in the
opposite direction of lophophore flow
Lophophorate
water
water
Entoproct

29. developing larvae may be found
attached to inside of calyx
Phylum Entoprocta
family Pedicellinidae
Barentsia benedeni
calyx, with fringe
of tentacles
stalk may have up
to 12 joints on older
individuals

30. Phylum Cycliophora ~5 species Close-up of mouthparts of
Norwegian lobster, showing…
Symbion
pandora

31. Phylum Cycliophora First reported in 1995 Entire phyla are still
waiting to be discovered
used to stick to
lobster mouth

32. Phylum Phoronida - worm-like body inside a chitin tube
2 genera
14 species
- worm-like body inside a chitin tube
- body has a flappy prosome, mesosome w/ lophophore,
and an elongated trunk (metasome)
- U-shaped gut; mouth and anus very close together
1 pair of metanephridia, closed circulatory system
- gonads simple, temporary; separate sexes or hermaphrodites
- blastopore becomes mouth (protostome character)
unique actinotroch larvae

33. - lophophore is a double row of tentacles
- each tentacle contains blood vessel for
gas exchange, extension of coelom
- food particles brought into ring by current;
then trapped in mucus lining food groove
- gametes proliferate in metacoel of trunk,
released through nephridia, or ruptured out
of tentacle ends
.. similar to many annelid worms; is this
a synapomorphy or a case of
convergent evolution?

34. Phoronis vancouverensis
Few species = not evolutionarily successful
Can be very ecologically important, however; tubes can form
dense aggregations on local mudflats, creating habitat

35. Phoronis australis
commensals that attach to the tubes made by cerianthids,
a group of tube-building anemones that live in soft-sediments

36. Actinotroch larvae
- distinctive flattened head, body ringed with fat tentacles
- ring of cilia at base of body

37. Phylum Brachiopoda - body enclosed between 2 valves (dorsal + ventral)
350 living species
30,000 fossil species
Phylum Brachiopoda
- body enclosed between 2 valves (dorsal + ventral)
- live cemented to bottom, or dig with ventral foot-like pedicle
- valves lined by mantle, creating mantle cavity (as in molluscs)
- U-shaped gut, with or without anus
1-2 pairs of metanephridia,
open circulatory system
- separate sexes; temporary gonads
- blastopore closes;
mouth + anus form secondarily

38. valves house lophophore
inside mantle cavity

39. Brachiopod Filter Feeding
ciliary motion
water flow
- Water passes over lateral cilia bands,
which send particles to frontal bands by localized beat reversal
- Frontal cilia then re-direct particles to food groove

40. Class Inarticulata Class Articulata
- shells may be equal, - shells usually unequal
especially in burrowers
- valves not hinged; - valves hinged: ventral teeth
attached by muscles lock into dorsal socket
- lophophore w/out skeleton - lophophore w/ skeleton
- anus present - no anus

41. Articulate Brachiopod
- Ventral valve bears teeth that lock into dorsal valve socket
- Adductor muscles close valves; diductors open valves
- contrast w/ bivalve, where springy ligament forces shell
valves open if adductor muscles relax

42. Brachiopod vs. Bivalve umbo is dorsal top valve is dorsal ventral

43. Brachiopod vs. Bivalve evolutionary loser evolutionary winner
350 living spp ,600 living spp.
Bivalves and brachiopods compete for the same resources;
bivalves have been come dominant, while most brachiopods
went extinct
Key bivalve innovation may have been the mantle fusing into
a siphon for drawing water into the shell