Transcript Porifer, Cnidarians, and Worms

SpongesPhylum Porifera
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Characteristics of Porifera:1)No definite symmetry.
2)Body multicellular, few tissues, no
organs.
3)Cells and tissues surround a water
filled space but there is no true body
cavity.
4)All are sessile, (live attached to
something as an adult).
5)Reproduce sexually or asexually,
sexual reproduction can be either
gonochoristic or hermaphroditic.
 6)Has no nervous system.
7)Lives in aquatic environments,
mostly marine.
8)All are filter feeders.
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Brain coral
Cnidarians
 Characteristics
 Includes marine organisms such as jelllyfish,
Portuguese man-of-war, coral, sea anemone,
& sea fans
 All carnivorous
 Have 2 cell layers
 Single opening (mouth/anus) to
gastrovascular cavity where food & water
enter & wastes leave; called two-way
digestive system
 Have tentacles around mouth to pull in water
& capture food
 Have a simple nerve net with to help with
movement & senses
 Sessile members include corals, sea
anemones, & sea fans
 Have radial symmetry as adults
 Contain stinging cells called cnidocytes in
their tentacles that contain coiled stingers
called nematocysts that can shoot out &
paralyze prey
 Body Forms
 Have 2 basic body forms ---polyp & medusa
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MEDUSA
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POLYP
Polyp forms are usually sessile with upright
tentacles arranged around the mouth at the top and
with a thin layer of mesoglea
Polyps are the asexual stage
Corals, hydra, & sea anemones exist in the polyp
form as adults
CORAL POLYPS
Medusa forms are usually free-swimming, bellshaped animals with tentacles that hang down
around the mouth and with a thick layer of mesoglea
for support
Medusa are the sexual stage
medusa
Polyp
Platyhelminthes
 The flatworms (Phylum
Platyhelminthes from the Greek
platy, meaning "flat" and helminth,
meaning worm)
 simple soft-bodied invertebrate
animals. they are the largest phylum
of acoelomates.
 Flatworms are found in marine,
freshwater, and even damp terrestrial
environments.
 Most flatworms are free-living, but many are
parasitic.
 There are three classes:
 Trematoda (flukes),
 Cestoda (tapeworms),
 and Turbellaria- planarian
Flatworms--- There is no true circulatory or respiratory
system, but like all other animals,
flatworms do take in oxygen.
 Usually the digestive tract has one
opening
 Flatworm reproduction is hermaphroditic,
meaning each individual produces eggs
and sperm. When two flatworms mate,
they exchange sperm so both become
fertilized.
Planarian
- Free-living flatworm
 Feed on dead or slow moving organisms
 Pharynx- food is sucked up and digested
in individual cells
 Have a nerve net
 Simple nervous system- 2 nerve cords
 Eyespots- detect light and dark
 Reproduce asexually by regeneration
 Reproduce sexually (hermaphrodites)
Tapeworm- Cestoda
 Tapeworms can grow 15 to 30 feet (9.1 m) in
length.
 The largest tapeworms grow up to 59 feet
(18 m)
 Most tapeworms enter humans through
infected food, the same way they enter pets
 . Tapeworms harm their host by stealing vital
nutrients, causing malnutrition and, if left
untreated, can cause intestinal blockage.
 The tapeworms have long, flat bodies that are divided
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into three sections:
the scolex, the neck and the proglottid.
The scolex contains several suckers and may have
hooks.
Each proglottid contains a complete set of male and
female reproductive organs that produce sex cells.
Proglottids are formed in the section at the base of the
neck, with the maturing ones moving farther back as
new ones are formed in front of them.
The proglottids near the end of the body form mature
eggs. As these eggs are fertilized, the zygotes in the
very last segment begin to differentiate and these
segments become filled with embryos.
Proglottids also contain muscles, nerves, flame cells.
Proglottids may contain up to 100,000 eggs.
Tapeworms
 At least 125 million humans are infected with
the tapeworm disease.
Flukes---Parasitic
Embeds in organs where it
feeds.
Life cycle may include one ,
two, or more hosts.
The nematodes
roundworms are one of the most
common phyla of animals
Reproduction is usually sexual.
Males are usually smaller than
females (often much smaller) and
often have a characteristically
bent tail for holding the
female
for copulation.
 Nematodes commonly parasitic on humans
include whipworms, hookworms, pinworms,
ascarids
Pin worms
 Pinworms are about the length of a staple
and live in the rectum of humans. While an
infected person sleeps, female pinworms
leave the intestines through the anus and
deposit eggs on the surrounding skin.
 Itching around the anus
 Pinworm is the most common worm infection
in the United States. School-age children,
followed by preschoolers, have the highest
rates of infection.
Trichnella……
 Trichinellosis, also called trichinosis, is
caused by eating raw or undercooked meat of
animals infected with the larvae of a species
of worm called Trichinella.
 Nausea, diarrhea, vomiting, fatigue, fever,
and abdominal discomfort are the first
symptoms of trichinellosis. Headaches,
fevers, chills, cough, eye swelling, aching
joints and muscle pains, itchy skin, diarrhea,
or constipation follow the first symptoms.
Ascaris….
ovaries
intestines
Prevention of Worms????
Wash hands
Cook meat thoroughly
Wash vegetables.