Lesson 5d. Bilateral Acoelomates Flashcards
Animals that seek food, shelter, home sites, and nates require a different set of strategies and radially symmetrical sessile
Phylum platyhelminthes: flatworms
An evolution that has concentrating sense organs in the head region
Cephalization
Evolution that says it is divided along only 1 plane of symmetry to yield 2 mirror image
Bilateral symmetry
Only one internal space, the digestive cavity, without coelom
Acoelomates
Have 3 germ layers (endoderm, ectoderm, mesoderm)
Triploblastic
The blastopore becomes the mouth
Protostomes
It has one opening
Incomplete gut
Mm to m in length, some free living, others parasitic
Phylum platyhelminthes
3 class of platyhelminthes
Class trematoda, cestoda, turbellaria
Free living forms, most are bottom dwellers in marine/freshwater
Class turbellaria
Found in streams, pool, and hot springs
Freshwater planarians
They are limited to moist places
Terrestrial flatworms
Most turbellaria have ____, ciliated ___ on the basement membrane
Cellular
Epidermis
Most turbellarians have ______
Dual-gland adhesive organs
Fasten microvilli of other cells to substrate
Viscid gland cells
Secretion of ___ provides a quick chemical detachment
Gland cells
Carnivorous and detect food by chemoreceptors
Planaria
Wrap themselves around prey and extend the pharynx to suck up food
Planaria
Feed on host cells, cellular debris, and body flyids
Trematodes (parasitic flukes)
Rely on hosts digestive tract and absorb digested nutrients
Cestodes(tapeworm)
Flatworms have a kidney called____, used for osmoregulation
Protonephridia
It resembles nerve net of cnidarians
Subepidermal nerve plexus
Bilobed cerebral ganglion (mass of nerve cells) anterior to the ventral nerve cords
Brain
Sense organ: present in turbellarians, and larval trematodes, light-sensitive eyespots
Ocelli
Sense organ: abundant
Tactile and chemoreceptive cells
Sense organ: equilibrium and sense of direction of water current
Statocysts and rheoreceptors
Many turbellarians constrict behind the pharynx and separate into two animals, each half regenerates the missing part
Fission
If tail/head are cut off, each grows the missing parts; it retains polarity
Regeneration
Nearly all turbellarians are monoecious but they ____
Cross-fertilize
One or more testes are connected to one vas deferens (runs to a seminal vesicle)
Male structure
Nipple-like penis or extensible tentacles
Copulatory organ
Develop male and female organs opening at a common pore
Turbellarians
Free-living, range from 5mm -50 cm, move by cilia, glide over a slime track secreted by adhesive glands
Class turbellaria
Parasitic flukes, resembles turbellaria but the tegument (skin) lacks cilia in adults, sense organs are poorly developed
Class trematoda
Trematoda life cycle
Egg- definitive host- miracidium- sporocyst- rediae- cercariae- metacercaria
Free swimming ciliated larva
Miracidium
Juvenile flukes
Metacercaria
Adult flukes live in bile passageways in the liver of sheep
Sheep liver fluke (Fasciola hepatica *italicized)
Process of sheep liver fluke
Egg
Passed in feces
Miracidia enters the snail
Becomes sporocysts
Two generations of rediae
Cercariae encyst on vegetation
Metacercaria, when eaten
MOst important han liver fluke
Clonorchis sinensis (italicized
It is common in china Japan southeast Asia (bicol)
Clonorchis sinensis (italicized): human liver fluke
Also infects cats, dogs, pigs, 10-20mm long with oral and ventral sucker (adult)
Clonorchis sinensis (italicized): human liver fluke
Clonorchis life cycle
Adults live in bile passageway
Egg completes miracidium
Eaten by snail to form sporocyst
Produce rediae
Turns to tadpole-like cercariae
Metacercariae cyst
Cyst goes to the bile duct
How to control human liver fluke
Destroy snails and thoroughly cook fish
This are blood flukes
Schistosoma
Over 200 million people infested with ____ which is common in africa, south America, west indies, middle and far east
Schistosomiasis (italicized)
It has separate sexes with 3 species varied with location;
Schistosoma
-large intestine
-small intestine
-urinary bladder
Schistosoma life cycle
Egg discharged in feces/urine
Hatch as a ciliated miracidia
Snail transforms it to sporocyst
Produce cercariae
Penetrates the skin
Enters blood vessels to hepatic portal blood vessels
Develop in the liver
Eggs that remain behind become center of
Inflammation
How to control blood flukes
Proper disposal of human wastes
A swimmer’s itch that occurs when cercariae penetrate an unsuitable host causing inflammation or itch
Schistosoma dermatitis
Its normal host many be bird or others
Schistosoma dermatitis
In class cestoda, these have long flat bodies with scolex
Tapeworms
Holdfast structure with suckers and hooks
Scolex
Scolex is followed by a linear series of reproductive units or
Proglottids
They lack digestive system and sensory organs except for cilia
Class cestoda
______ is has no cilia
Tegument
Entire surface of cestodes is covered with ____ similar to microvilli seen in intestines
Projection (microtriches)
Increases the surface area for food absorption
Microtriches
Require two host which adult is parasitic in the digestive tract
Class cestoda
How many species of tapeworms are known
1000 species
Most do little harm to host
Tapeworms
It is a beef tapeworm
Taenia saginata (italicized)
Lives as an adult in digestive canals of human, juvenile form found in intermuscular tissue of ______
Taenia saginata (italicized)
Cattle
______ has 4suckers but no hooks
_______ pass in feces, single ______ rupture as they dry
Scolex
Gravid proglottids (with shelled, infective larvae
Proglottids
Beef tapeworm life cycle
Cattle swallow larvae hatch as oncospheres
Oncospheres use hooks to burrow in intestinal wall
Encyst to become bladder worms
Meat is eaten, cyst wall dissolves
Scolex invaginates to attach to intestinal wall
New proglottids develop in 2-3weeks
How to avoid beef tapeworm
Eat only thoroughly cooked beef
Pork tapeworm
Taenia solium (italicized)
Fish tapeworm
Diphyllobothrium latum(italicized)
Unicellular hydatid
Echinococcus granulosus (italicized)
