Nematomorpha, Acantocephala, Annelida

Question 1

Gordius sp

Answer 1

Phylum Nematomorpha
Found in water containers or damp garden soil
Does not harm humans, animals or plants
White when they emerge from host, then turn yellowish-tan to brownish black
Knot themselves into a ball like shape (resemble “Gordian Knot”)

Question 2

Phylum Nematomorpha

Answer 2

Phylum of pseudocoelomates - no real body cavity(horsehair worms)
Found in ponds and streams, parasitize arthropods
No excretory or circulatory system, only a vestigial digestive tract
Larva penetrate any convenient aquatic animal, but has to develop in insect

Question 3

Phylum Acanthocephala

Answer 3

Thorny-head worms
Primitive, unsegmented, rare
Inhabit intestines of fish, amphibians, birds and mammals
Reduced muscular, nervous, circulatory, and excretory systems, NO digestive system
Basically just a bag of reproductive organs with a spiny holdfast at one end
2 hosts

Question 4

Generalized life cycle for Acanthocephala

Answer 4

Egg –> Acanthor (resting, resistant stage) –> Acanthella (in 1st intermediate host) –> Cystacanth (infective larval stage in 2nd intermediate host) –> Adult

Question 5

Acanthocephala sp

Answer 5

Males and females have retractile proboscis and embryonic hooklets
Protonephridia for excretory system is a distinctive feature
Lack a digestive system and body cavity
Males have a proboscis receptacle and 2 testes within a ligament sac at mid body
Female has uterus with eggs
Common in birds and fish (not often human parasites)

Question 6

Phylum Annelida

Answer 6

Earthworms, polychaete worms, leeches
All members are segmented (segmentation also called metamerism)
Each segment contains elements of circulatory, nervous, and excretory tracts
Metamerism increases efficiency of body movement by allowing the effect of muscle contraction to be localized

Question 7

Placobdella sp

Answer 7

Phylum Annelida, Class Hirdinea
Common parasites of amphibians and reptiles
Several species serve as vectors for other parasitic diseases

Question 8

Hirudo medicinalis

Answer 8

Phylum Annelida
Medical leeches
Secrete anaesthetic to numb skin while biting, also produce anticoagulant (Hirudin)
Eat only 2X a year, bloat up to 11 times their body size

Question 9

Macrocanthorhynchus hirudinaceus

Answer 9

Giant thorny-headed worm of the pig
Phylum acanthocephala
Intermediate host usually beetles or june bugs

Question 10

Haemocoel

Answer 10

Body cavity of the insect

Where the acanthocephala larva migrate to

Question 11

How does hirudin work?

Answer 11

It is an anticoagulant
Works by inhibiting thrombin (normally responsible for converting fibrinogen into fibrin blood clots)
By inactivating thrombin, no solid blood clots can form. It also limits the ability of platelets to stick together and initiate clots