nemertea ribbon worms. development bilateral symmetry three germ layers acoelomate (coelom in...
TRANSCRIPT
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)
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/files/Bio%20102/Bio%20102%20lectures/Animal%20Diversity/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 ladder-like 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 (free-living)
• 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 REPRODUCTION
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
Parthenogenesis is when the female can have a growth that separates into an offspring
They also can reproduce sexually
WHIP WORM C. ELEGANS
PSAMMOMERMIS
AFRICAN SPIRAL NEMATODE
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.