Zoology Test 2b Flashcards Preview

Zoology > Zoology Test 2b > Flashcards

Flashcards in Zoology Test 2b Deck (23)
Loading flashcards...

How important are nonparasitic nematodes in world?

- extremely important as detritivores
- ubiquitous = everywhere
- pseudocoelomates (false body cavity (coelom))


origin of pseudocoelom

- start with blastula with blastocoel in center
- blastopore starts to form
- blastocoel becomes pseudocoelom
- which creates the first complete digestive tract with mouth and anus


characteristics of nematodes

- superficially simple
- little if any cephalization
- only longitude muscles are present
- no cilia, so no flame cells
- almost all dioecious
- no sexual reproduction just asexual



refers to head


advantages of nematodes

- psuedocoelom gives them certain advantage over acoelomates
- have hydrostatic skeleton
- space for organs
- can circulate materials internally
- complete digestive system/tract


excretion and osmoregulation in nematodes

- no flame cells
- excrete ammonia which diffuses across body wall
- osmoregulation is poorly understood


circulation and respiration in nematodes

- no circulation or respiration systems


parasitic nematodes

- easy to break the life cycle, very specific life cycle
- produce tremendous amount of eggs per adult
- just sexual reproduction
- hookworm, pinworm, whipworm


life cycle of Ascaris

- medically important parasite
- lay 200,000 eggs per day
- juveniles develop inside shells and can remain viable on snail or plant for months or years in conditions are right
- eggs ingested with unwashed veggies or via unsanitary habits
- eggs hatch in digestive system, burrow through intestinal walls into veins and lymph vessels and finally carried to lungs
- larva enters lungs causing serious infection
- larvae eventually coughed up and swallowed then mature in intestines and feed


symptoms of ascaris infection

- if infection heavy, abdominal symptoms, allergic reaction, wandering worms
- can have no symptoms


Taxocara in animals

- commonly found in dogs and cats
- simple life cycle
- juveniles remain in state of arrested development unless female becomes pregnant, then infect embryos in uterus>>puppies born with worms


Taxocara in humans

cannot complete development in humans, but cause damage by wandering worms (visceral larva migrans)


characterisitics of Necator americanus

- nematode parasite
- hookworm known as 'American Killer'
- relatively light infection can cause mental retardation in children, retarded physical growth and loss of energy
- poor ppl mostly affected
- causes anemia>> low oxygen, not enough RBC's


similarities of necator to ascaris and taxocara

- larvae passes from bloodstream to lungs and then to digestive system
- differs b/c eggs hatch in moist soil and juvenile worms penetrate vare feet
- life cycle broken by wearing shoes


characteristics of trichinosis

- disease caused Trichinella spiralis
- is an intestinal parasite as adult
- differs b/c bloodstream carries larvae to muscle instead of gut
- encyst in muscle
- larvae causes painfully encysted muscles
- no cure exists


characteristics of pinworm

- also called Enterobius sp.
- most common nematode parasite in us population
- 30% of children infected
- live in large intestine and cause itching
- females lay eggs in perianal region
- host scratches, which contaminates hands, everything
- simple life cycle



means 'thread-ike'


characteristics of Wucheraria sp.

- type of filarial worm
- 250 million worldwide
- causes elephantiasis


life cycle of filarial worms

- bitten by infected mosquitoes all filarial worms are transmitted by mosquito
- adults live in the lymph glands causing blockages that lead to dramatic swelling
- other filarial worms live in other tissues, causing various types of damages


characteristics of Onchocercus

- type of filarial worm
- causes river blindness
- embeds itself in cornea


characteristics of Dirofilaria sp.

- type of filarial worm
- causes dog heartworm
- transmitted by mosquito
- infects heart
- cats, ferrets, sea lions, wolves, coyotes, foxes and other mammals


characteristics of Dracunculus

- type of filarial worm
- nematode parasite
- lives just under skin of human host and sheds larvae directly from open sore into water
- intermediate host is a cyclops
- can be up to three feet long



a small crustacean similar to Daphnia