Lophotrochozoa

1
Lophotrochozoa Minor Phyla
2
Eutrochozoa Rotifera, Acanthocephala,
Entoprocta,Platyhelminthes, Nemertea, Mollusca,
Sipuncula, Annelida
Lophotrochozoa
Lophophorata Ectoprocta, Brachiopoda, Phoronida
Protostomia
Ecdysozoa Onychophora, Tardigrada, Arthropoda,
Nematoda, Nematomorpha, Kinorhyncha, Loricifera,
Priapulida
Cuticulata
Gastrotricha
3
Platyhelminthes
Parenchymia
Nemertea
Annelida
Mollusca
Sipuncula
Entoprocta
Rotifera
Acanthocephala
Lophotrochozoa
Ectoprocta
Lophophorata
Brachiopoda
Phoronida
4
Phylum Sipuncula

• The Phylum Sipuncula (from Latin meaning little
  pipe) consists of approximately 250 species of
  benthic, marine wormlike animals, most from 15-30
  cm in length (range 2mm to 70cm).
• Sipunculids produce a trochophore larva similar
  in structure to that of the annelids.

5
Phylum Sipuncula

• Sometimes referred to as the peanut worms
  (probably for the gridlike pattern on their
  epidermis) most sipunculids burrow in sand or
  silt or occupy crevices or empty mollusc shells
  or worm tubes

6
http//www.glaucus.org.uk/Sipunculus-nudus-RL.jpg
7
Sipunculid clip

• One minute clip of sipunculid
• http//www.youtube.com/watch?vS1zQCa5cfcQ

8
Phylum Sipuncula

• The body is unsegmented and divided into an
  anterior introvert and a posterior trunk.
• The introvert is a retractile structure at the
  anterior end of the animal and can be half the
  body length.
• Sipunculids have a fluid filled coelom and a
  hydrostatic skeleton. The pressure of the fluid
  in the coelom is used to extend the introvert.

9
http//www.eol.org/pages/8871
10
Phylum Sipuncula

• Sipunculids are generally non-selective deposit
  feeders and they use the ciliated tentacles or
  lobes surrounding the tip of the introvert to
  collect food.
• They eat a variety of small easy to acquire food
  items algae, unicellular organisms, larvae and
  detritus

11
Phylum Sipuncula

• The introvert is also used to burrowing into
  sediments.
• Coelomic pressure is used to extend the introvert
  into the sediment and anchor it in place.
  Retractor muscles then contract pulling the
  introvert forward and drawing the rest of the
  animal forward.

12
Sipunculid clip

• Sipunculid burying itself one minute
• http//www.youtube.com/watch?vaq6kEX9igeI

13
Platyhelminthes
Parenchymia
Nemertea
Annelida
Mollusca
Sipuncula
Entoprocta
Rotifera
Acanthocephala
Lophotrochozoa
Ectoprocta
Lophophorata
Brachiopoda
Phoronida
14
Phylum Entoprocta

• AKA the kamptozoans or the goblet worms,
  entoprocts are small (1cm), sessile marine
  animals most of which are colonial.
• The body, which is covered by a thin external
  cuticle consists of a long mobile contractile
  stalk topped by a calyx, which contains the
  organs and a crown of tentacles.

15
http//www.biocyclopedia.com/index/general_zoology
/phylum_entoprocta.php
16
Phylum Entoprocta

• Entoproct means anus inside and this refers to
  the fact that the mouth and the anus are
  surrounded by the ring of tentacles.
• The tentacles are solid and non rectracile,
  Instead they can be rolled up and covered by the
  intertentacular membrane.

17
Phylum Entoprocta

• Entoprocts occur in shallow water and feed on
  suspended particles that they trap using mucus
  covered cilia on their tentacles.
• The food is directed down the tentacles to the
  mouth.

18
Phylum Entoprocta

• Reproduction occurs either asexually by budding
  or sexually (they are hermaphroditic).
• Fertilized eggs are incubated in a pouch within
  the calyx and the embryos are fed by parental
  cells. The embryo develops into a free-swimming
  trochophore larva that settles and metamorphoses
  into the adult form.

19
Platyhelminthes
Parenchymia
Nemertea
Annelida
Mollusca
Sipuncula
Entoprocta
Rotifera
Acanthocephala
Lophotrochozoa
Ectoprocta
Lophophorata
Brachiopoda
Phoronida
20
Phylum Rotifera

• Rotifers are named for their characteristic
  ciliated crown or corona, which when it beats
  looks like a rotating wheel.
• Rotifers are tiny animals (most are 100-300µm
  long and the largest only 3mm long) the majority
  of which live in freshwater and are benthic
  inhabitants (live on the bottom).
• About 2000 species have been described.

21
9.1
22
Phylum Rotifera

• The beating of the cilia in the corona draws in
  plankton-containing water for food.
• The mouth opens to a modified muscular pharynx
  known as a mastax, which is a structure unique to
  rotifers.
• The mastax has a set of complex jaws, which are
  used to grasp and chew food.

23

• Rotifer video 1 minute
• http//www.youtube.com/watch?vcYNJOVDQexA

24
Phylum Rotifera

• One group of rotifers, the Bdelloid rotifers, are
  very unusual in that there are no males,
  hermaphrodites, or evidence of meiosis.
• Molecular evidence suggests that there has been
  only asexual reproduction in this group for
  several million years.

25
http//www.arcodiv.org/seaice/rotifers/Antarctic_r
otifer_Philodina_gregaria_400x300.jpg
26
Phylum Rotifera

• Because of the problem of accumulation of
  deleterious mutations in lineages of exclusively
  asexually reproducing animals (a process known as
  Mullers ratchet) it is unclear how the bdelloids
  have been able to dispense with sexual
  reproduction entirely.
• Other rotifers reproduce using a combination of
  sexual and asexual reproduction.

27
Platyhelminthes
Parenchymia
Nemertea
Annelida
Mollusca
Sipuncula
Entoprocta
Rotifera
Acanthocephala
Lophotrochozoa
Ectoprocta
Lophophorata
Brachiopoda
Phoronida
28
Phylum Acanthocephala

• Acanthocephalans are commonly known as
  spiny-headed worms because of the spiny eversible
  proboscis they use to attach to the gut of their
  host.
• All 1100 species of Acanthocephalan are
  endoparasitic and most parasitize fish, birds and
  mammals. Most small 1mm to 3-4cm a few up to 1m
  long.

29
http//rydberg.biology.colostate.edu/Dissections/a
canthocephala/acanthfemmal.jpg
30
Phylum Acanthocephala

• Bilaterally symmetrical
• No gut
• Body unsegmented
• Prominent spiny proboscis
• Body cavity is a pseudocoelom (mesoderm lines
  only outer edges of blastocoel, body cavity not
  lined with peritoneum).
• No respiratory or circulatory system
• Simple nervous system single anterior ganglion
  with connecting nerves to organs.

31
9.3
32
http//upload.wikimedia.org/wikipedia/commons/9/99
/Acanthocephala_Rhadinorhynchus.jpg
Acanthocephalan proboscis
33
Phylum Acanthocephala

• Body wall covered with numerous minute
  depressions which increase the surface area of
  tegument and facilitate (as in cestodes)
  absorption of food from hosts gut.
• As in cestodes, Acanthocephalans lack a gut.

34
Phylum Acanthocephala

• Acanthocephalans have a lifecycle in which a
  vertebrate is the definitive host (in alimentary
  canal) and an invertebrate the intermediate host.
• Acanthocephalans, as other parasites do, modify
  the behavior of the intermediate host to enhance
  the chances of its being eaten.

35
Phylum Acanthocephala

• For example, acanthocephalans that parasitize
  Gammarus, a small freshwater crustacean, cause
  the Gammarus to alter its behavior in the
  presence of ducks, a common predator.
• Instead of diving to the bottom when a duck
  appears, the Gammarus swims into the light and
  grasps tightly onto a piece of vegetation,
  greatly increasing its chances of being eaten.

36
Phylum Acanthocephala

• The change in behavior appears to be caused by
  the Acanthocephalan pumping a serotonin-boosting
  molecule into the Gammarus brain.
• This causes the Gammarus to think its having sex
  and cling as it would if mating. Interestingly,
  the parasites manipulation also causes female
  Gammarus to mimic the males mating behavior.

37
Phylum Acanthocephala

• Another Acanthocephalan that parasitizes pill
  bugs causes them to reverse their normal behavior
  and avoid humid, dark areas.
• Instead they wander in the open where they are
  much more vulnerable to birds, the
  acanthocephalans definitive host.
• The parasites manipulations are very effective.
  Although fewer than 1 of pill bugs are typically
  infected with acanthocephalan parasites, 30 of
  pill bugs delivered to nestlings are infected.

38
Platyhelminthes
Parenchymia
Nemertea
Annelida
Mollusca
Sipuncula
Entoprocta
Rotifera
Acanthocephala
Lophotrochozoa
Ectoprocta
Lophophorata
Brachiopoda
Phoronida
39
Phylum Ectoprocta

• Also known as the bryozoans or moss animals they
  are small (lt0.5mm) colonial animals, but colonies
  can be up to 1 meter across (although most are
  10cm or so)
• Most are marine and form masses on rocks and
  other substrates where they feed on phytoplankton
  and other small organisms which they catch using
  cilia on their lophophore.

40
Lophopodella carteri
lophophore
http//www.bio.umass.edu/biology/conn.river/bryozo
a.html
41
Phylum Ectoprocta

• Individual zooids are genetically identical.
• The zooids are connected to each other and
  surrounded by a protective calyx as in
  entoprocts.
• Most zooids are feeding zooids called autozooids.
  These use the lophophore to feed. The tentacles
  are extended by hydrostatic pressure and prey is
  trapped using cilia

42
Phylum Ectoprocta

• The lophophore and mouth are mounted on a tube
  called an invert that can be everted through an
  opening in the calyx and rapidly withdrawn if
  threatened.
• The mouth is found within the ring of tentacles
  but the anus is outside the ring (in contrast to
  entoprocts).

43
Phylum Ectoprocta

• Other types of zooids include spinozooids which
  possess protective spines, gonozooids, which act
  as brood chambers for developing eggs and
  modified autozooids called avicularia which use a
  modified operculum to snap at threatening
  organisms.

44
www.marlin.ac.uk
45
Phylum Ectoprocta

• Colonies of ectoprocts in freshwater temperate
  habitats die in the fall, but leave behind
  statoblasts, which are groups of cells
  surrounded by a protective envelope.
• Zooids emerge in the spring and a new colony
  forms by budding.

46
Phylum Ectoprocta

• Ectoprocts have a rich fossil record and over
  15,000 fossil species have been described.
• Fossils are known from as far back as the
  Cambrian period (500mya).

47
Phylum Ectoprocta

• Ectoproct video 1 minute
• http//www.youtube.com/watch?vtpifpqrQKRA

48
Platyhelminthes
Parenchymia
Nemertea
Annelida
Mollusca
Sipuncula
Entoprocta
Rotifera
Acanthocephala
Lophotrochozoa
Ectoprocta
Lophophorata
Brachiopoda
Phoronida
49
Phylum Brachiopoda

• Greek brachion branch pous foot.
• The living brachiopods are the remnants of a once
  much more diverse group. There are about 335
  living species vs gt 26,000 fossil species.
• Superficially similar in lifestyle and external
  appearance to bivalve molluscs.

50
http//paleo.cortland.edu/tutorial/Brachiopods/Bra
chiopod20Images/lingula.GIF
51
Brachiopod characteristics

• The body is enclosed within a symmetrical bivalve
  shell as is the case in molluscs. However,
  unlike molluscs brahiopods have a dorsoventrally
  oriented shell with two unequally sized valves
  unlike molluscs which have left and right valves.

52
Phylum Brachiopoda

• Brachipods possess a stalk or pedicle (1-30cm in
  length), which is typically attached to rock or
  anchored in sediment
• A large, anterior mantle cavity contains the
  lophophore which is used for suspension feeding.

53
Brachipod cross section http//aalliiffaazzeellii
.googlepages.com/pra1.gif  Principal organs of a
brachiopod as typified by Terebratulina. (After
R. C. Moore, ed., Treatise on Invertebrate
Paleontology, pt. H, Geological Society of
America, Inc., and University of Kansas Press,
1965)
54
Phylum Brachiopoda

• The lophophore occupies much of the internal
  space of the brachipod and has a branched rather
  than circular structure (hence the name as brach
  means a branch) with complex folding of the
  lophophore being common.

55
http//rydberg.biology.colostate.edu/Dissections/t
erint.htm
56
Phylum Brachiopoda

• Brachipods are entirely marine and most occur in
  areas without strong waves or currents.
• They occur at depths ranging from the intertidal
  to the deep sea.

57
Platyhelminthes
Parenchymia
Nemertea
Annelida
Mollusca
Sipuncula
Entoprocta
Rotifera
Acanthocephala
Lophotrochozoa
Ectoprocta
Lophophorata
Brachiopoda
Phoronida
58
Phylum Phoronida

• Sometimes called horseshoe worms they build tubes
  of chitin and filter feed using a lophophore.
• The are marine and occur in sediments between the
  intertidal and about 400m depth.

59
Phylum Phoronida

• Most phoronids range in length from 2-20cm, but
  can reach 50 cm.
• They secrete a tube of chitin and the lower end
  of the animal is swollen into an ampulla, which
  anchors the animal and allows it to quickly
  retract its lophophore into the tube.

60
Phylum Phoronida

• Phoronids can be extremely abundant numbering
  thousands of individuals per sq. meter. They are
  unpalatable to many predators and that likely
  explains the high densities.

61
Phylum Phoronida

• Phoronids feed on a variety of small filterable
  prey including algae, small invertebrates and
  flagellates which are caught using the lophophore.

62
Phylum Phoronida

• Some species are hermaphroditic and the rest
  dioecious. Eggs are in many species brooded for
  a while before being released into the water.
• Most species develop free-swimming larvae that
  feed on plankton that they catch using tentacles.

63
Phoronid larva (they are called actinotrochs
http//en.wikipedia.org/wiki/FilePhoronid_ASlotwi
nski.jpg
64
Phylum Phoronida

• After a larval period of about 20 days the larva
  settles on the bottom and in about 30 minutes
  undergoes a rapid metamorphosis in which the
  larval hood and tentacles are reabsorbed, the
  adult lophophore is formed and the gut forms a
  u-bend with the anus opening outside the
  tentacles.

65
Phylum Phoronida

• There are only a dozen described species, but
  this is certainly an underestimate as more than
  25 larval forms have been described.

66
Phylum Phoronida

• Phoronid worm (1 minute)
• http//www.youtube.com/watch?vj-Z1bibYY1w