Zoology Test 2b

Question 1

How important are nonparasitic nematodes in world?

Answer 1

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

Question 2

origin of pseudocoelom

Answer 2

• 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

Question 3

characteristics of nematodes

Answer 3

• 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

Question 4

cephalo

Answer 4

refers to head

Question 5

advantages of nematodes

Answer 5

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

Question 6

excretion and osmoregulation in nematodes

Answer 6

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

Question 7

circulation and respiration in nematodes

Answer 7

• no circulation or respiration systems

Question 8

parasitic nematodes

Answer 8

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

Question 9

life cycle of Ascaris

Answer 9

• 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

Question 10

symptoms of ascaris infection

Answer 10

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

Question 11

Taxocara in animals

Answer 11

• 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

Question 12

Taxocara in humans

Answer 12

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

Question 13

characterisitics of Necator americanus

Answer 13

• 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

Question 14

similarities of necator to ascaris and taxocara

Answer 14

• 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

Question 15

characteristics of trichinosis

Answer 15

• 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

Question 16

characteristics of pinworm

Answer 16

• 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

Question 17

filarial

Answer 17

means ‘thread-ike’

Question 18

characteristics of Wucheraria sp.

Answer 18

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

Question 19

life cycle of filarial worms

Answer 19

• 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

Question 20

characteristics of Onchocercus

Answer 20

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

Question 21

characteristics of Dirofilaria sp.

Answer 21

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

Question 22

characteristics of Dracunculus

Answer 22

• 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

Question 23

cyclops

Answer 23

a small crustacean similar to Daphnia