The Kingdom Animalia
 Do worms make you
squirm?
 Phyla Platyhelminthes,
Nematoda, and
Annelida
Phylum Platyhelminthes
 The platyhelminthes
is the first of three
phyla that are made
up of worms.
 The platyhelminthes
are the flatworms.
The flatworms
 Unlike the porifera and the
cnidarians, flatworms exhibit three
cell layers as will all animal phyla
from this point on.
 Flatworms have a basic digestive
tract that is two-way.
 This means that food is ingested
and solid wastes are eliminated
through the same opening.
Body plan
 Flatworms exhibit bilateral
symmetry, just like you do.
 Flatworms are capable of
amazing feats of regeneration.
 Cut a flatworm in half, and two
worms will grow.
 A whole new flatworm can
grow just from a piece of
another flatworm
Flatworm feeding
 Marine and aquatic
flatworms are carnivorous
predators and scavengers.
 Other flatworms, such as
flukes and tapeworms are
parasites.
 Tapeworms can grow to
lengths of up to 50 feet!
Reproduction in flatworms
 As mentioned, flatworms can
reproduce asexually through
regeneration.
 They can also reproduce
sexually.
 Each flatworm is a
hermaphrodite, meaning that
they produce both sperm
cells and egg cells.
Phylum Nematoda
 Numerically the nematods are
the must abundant of all
animals. They are sometimes
called roundworms.
 A small sample of soil can
contail thousands of these tiny
worms.
 Some are predatory and feed on
bacteria.
 Many others are parasites of
insects and other larger animals
Body plan
 Nematods exhibit the
“tube within a tube”
body plan.
 They have a one-way
digestive tract, just like
we do.
 They are much more
complex than the earlier
phyla we’ve looked at
so far.
Reproduction
 The various ways that nematodes reproduce
is staggering.
 For our purposes we will simply say that
nematodes reproduce sexually.
Nematodes and humans
 First the bad news.
 There are several
diseases in humans which
are caused by nematodes.
 Of particular note is a
nematode called filaria.
 Filaria attacks the human
lymphatic system causing
the disease elephantitis
On the other hand
 Not all nematodes are bad.
 Many of them are helpful to
humans because they attack pests
which destroy our crops.
 They are used as biological control
agents.
 Some nematodes attack bugs and
insects, while others attack
dangerous types of nematodes.
Phylum Annelida
 Members of this phylum
are commonly referred to
as the segmented worms.
 The most common
member of this phylum is
the earthworm.
 Annelids are found in
marine environments,
freshwater and moist
terrestrial soils.
Bristle worm
Mildly toxic if handled
Body plan
 Like the other two worm
phyla, annelids display
bilateral symmetry.
 They have the tube within
a tube body plan.
 They are made up of
successive segements,
each containing the same
internal organs.
Reproduction
 Annelids are able to
reproduce asexually through
regeneration, but not to the
same extent as the
flatworms.
 All members are
hermaphrodites and are
able to reproduce sexually.
Feeding
 Earthworms feed by burrowing
through the soil, ingesting soil, and
digesting nutrients.
 Earthworm activity increases the
quality of the soil.
 Leeches are aquatic blood-sucking
parasites.
 Many marine annelids have powerful
jaws and are predatory.
 Deep sea vent tubeworms are also
annelids. They are fed by symbiotic
chemosynthetic bacteria.