Download Nemertea

Nemertea
Ribbon Worms
Development
• Bilateral Symmetry
• Three Germ Layers
• Acoelomate (coelom in
proboscis)
• Radial and Indeterminate body
development
•
Characteristics
•
•
•
•
•
•
•
Live in a Marine Environment
Dioecious (2 sexes)
Nervous System and Brain
Closed Circulatory System
Proboscis apparatus
Complete digestive tract
Carnivorous
Examples and Stories
• Lineus longissimus 30M long
and a few mm wide
• Reports of 60M
• Basiodiscus mexicanus
(at right)
• Archisymplectes (only
fossilized Nemertean)
• Gorgonorhynchus repens
(50mm long)
Lophophorate
Development
•
•
•
•
Bilateral
Acoelomate
Three Germ Layers
Radial division during
development
Characteristics
• A lophophore is a band of
cilliated tentacles
surrounding the mouth
• Lophophore are retractable
into coelom like space
Platyhelminthes
By: Ben, Matt, and Haram
Characteristics
• Flatworms have bilateral
symmetry.
• They have no true body
cavity except for the gut,
and are classified as
acoelmates.
• Their organ systems are
formed of ectoderm,
endoderm, and mesoderm.
Schistosoma Life Cycle
• Parasitic flatworms cause schistosoma in humans.
-Infection occurs when cercariae penetrate the skin while
in the water.
-The cercaria loses its tail becoming a schistosomule
which moves through various tissues to the veins.
-Adults mature in the in the veins surrounding the
intestines or bladder, depending on the species.
-Females release eggs which move from the veins to the
lumen of the intestine or the bladder. The eggs are then
passed from the body in the feces or urine.
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/fi
les/Bio%20102/Bio%20102%20lectures/Animal%20Dive
rsity/Protostomes/Lophotrochozoans/Lophotrochozoans.
htm
Trichinella Life Cycle
More Characteristics
• Flatworms move by waving hair
on their skin to propel
themselves forward.
• They also move by contracting
their muscles.
• Flatworm reproduction is
hermaphroditic- each individual
produces eggs and sperm.
• When two flatworms mate, they
exchange sperm so both
become fertilized.
Specialized Tissues
Flatworms have :
• A sac body plan, meaning they have one opening
that functions as both a mouth and an anus.
• A pharynx, which extends form the underside of
the flatworm and sucks up food through the mouth
• Flame cells that are used for excretion.
• Amazing regeneration capabilities.
Specialized Features
• Cephalization (consists of 2 brains called
ganglia and nerve cords arranged in a ladderlike configuration).
• Gastrovascular cavity functions similarly to that
of Cnidaria
• Planarians, in Class Turbellaria, have eyespots
that determines the presence and intensity of
light.
• The head (scolex) of the flatworms have hooks
and suckers which function as an anchor.
Different Types of Flatworms
• Free-living carnivorous planarians
• Parasitic flukes that feed off the blood of other
animals
• Parasitic tapeworms that live inside the digestive
tracts of other animals.
Examples of Flatworms
• Turbellaria (freeliving)
• Planaria
• Monogenea
(parasitic)
More Examples
• Cestoda : parasitic
tapeworms
• Digenea
Round worms

They have bilateral symmetry, and radial
symmetry
Nematoda
Rotifera





They have a simple nervous
system that includes a main
ventral nerve cord and a
smaller dorsal nerve cord
They use diffusion to
breathe
They don’t have an
circulatory system so the
fluid in their body moves
nutrients around
They are the simplest group
to have an complete
digestive system
They also have a three layer
cuticle to keep the body
from drying out

Nematoda and Rotifera
are Pseudocoelomates.
This is when the body
cavity is derived from
the mesoderm. The
tissues are only loosely
bound so it is not as
organized as an
coelomate
MOVEMENT


They use hydrostatic
skeleton which change
liquid pressure in the
body changing the
bodies shape causing
movement.
They also use
longitudinal muscles to
move their bodies side
to side
REPRODUCTION


Parthenogenesis is
when the female can
have a growth that
separates into an
offspring
They also can reproduce
sexually
WHIP WORM
C. ELEGANS
AFRICAN SPIRAL
NEMATODE
PSAMMOMERMIS
BANANA NEMATODE



They are a major cause important diseases of
plants, animals, and humans.
Diseases including filariasis, ascariasis, and
trichinosis
Some live in food products such as beer and
vinegar.