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Sze201 Fundamentals Of Arthropod Biology Question Paper
Sze201 Fundamentals Of Arthropod Biology
Course:Fundamentals Of Arthropod Biology
Institution: University Of Nairobi question papers
Exam Year:2006
Questions
1. Compare class Chilopoda and class Crustacea
2. What are the main features of Diplopoda?
3. Why we consider Pauropoda, Symphyla and Diplopoda resemble a combined taxa.
4. Are Onychophora and peripatus the same?
5. Explain the behavior of peripatus sp.
6. How many species belong to class Merostomata?
7. Write an article on the activity of Xiphosuran polyphemus (5 lines)
8. Meaning of extinct, fossil
9. Where the Subclass Eurypterida was found, what do you know about Eurypterus sp.
MARKING SCHEME
1. Compare class Chilopoda and class Crustacea
? The Chilopoda are called centipedes
? the body is flattened dorso-ventrally and consists of 15-173 segments each of which bears one pair of legs except the last two and one just back of the head. The latter bears a pair of poison claws called maxillipeds with which insects, worms, mollusks and other small animals are killed for food.
? The antennae are consisting of at least twelve segments
Internal anatomy
? The alimentary canal is simple; into it open the excretory organs (two malpighian tubules).
? The trachea are branched and open by a pair of stigmata in almost every segment.
? The reproductive organs are connected with several accessory glands. Eggs are usually laid.
Behaviour
? The centipedes are swift-moving creatures.
? Many of them live under the bark of logs or under stones.
? The genera Lithobius, Geophilus and Scutigera are common.
? The poisonus centipedes of tropical countries belong to the genus scolopendra. They may reach a foot in length and their bite is painful and dangerous to man
Fossil Chilopoda have been found in amber of oligocene age
? The Crayfish
? The lobster is so nearly like the crayfish in structure that the anatomical portion of this chapter may be applied also in large part to this animal.
? Common crayfish is Astacus fluvietilis
? External features
? Exoskeleton
? It is covered by an extremely hard chitinous cuticle impregnated with lime salts. This exoskeleton is thinner and flexible at the joints, allowing movements.
? Regions of the body
? It consists of two distinct regions, an anterior rigid portion the Cephalothorax and posterior series of segments, the abdomen. The entire body is segmented, but joints have been obliterated on the dorsal surface of the cephalothorax.
? It consists of a convex dorsal plate, the tergum, a ventral transverse bar, the sternum ,plates projecting down at the sides, the pleura and smaller plates between the pleura and the basis of the limb, the epimera.
Cephalothorax
? It consists of segments I-XIII which are enclosed dorsally and laterally by a cuticular shield, the carapace. An indentation, termed the cervical groove runs across the middorsal region of the carapace and obliquely forward on either side, separating the cephalic or head region from the posterior thoracic portion.
? The anterior pointed extension of the carapace is known as restorm. Beneath this on either side is an eye at the end of a movable peduncles.
? The mouth is situated on the ventral surface near the posterior end of the head region
2. What are the main features of Diplopoda?
a) The Diplopoda are called millipedes
b) The body is sub cylindrical and consists of from about 25 to more than 100 segments according to the species.
c) Almost every segment bears two pairs of appendages one or both pairs of legs on the seventh segment of the male are modified as copulatory organs.
d) The mouth parts are a pair of mandibles and a pair of maxillae.
e) One pair of short antennae and either simple or aggregated eyes are usually present.
f) There are olfactory hairs on the antennae and a pair of scent glands in each segment, opening laterally.
g) The scent glands of some have a toxic secretion containing hydrocyanic acid, some can discharge the secretion nearly a meter, the secretion of some tropical species have caused blindness in children.
h) The breathing tubes (tracheae) are usually unbranched, they arise in tuffts from pouches which open just in front of the legs.
i) The heart is a dorsal vessel with lateral ostia; it gives rise to arteries in the head.
j) The two or four excretory organs are threadlike tubes (Malpighian tubules), which pass their secretion into the intestine.
k) The millipedes move very slowly in spite of their numerous legs.
l) Sexes are separate, eggs are laid in damp earth.
m) Young have four segments and only three pairs of legs when they hatch, other segments are added in front of the anal segment.
Fossil millipedes have discovered in geological formations back to Devonian and Silurian
3. Why we consider Pauropoda, Symphyla and Diplopoda resemble a combined taxa.
The first three (Pauropoda, Symphyla and Diplopoda) are sometimes combined into a Superclass, the progoneta, characterized by reproductive organs that open to outside near the anterior end of the body,
4. Are Onychophora and peripatus the same?
Answer: yes
5. Explain the behavior of peripatus sp.
Habits and behaviour
? Peripatus lives in cervices of rocks, under bark and stones and in other dark moist places and is active only at night.
? As animal moves by means of its legs, the two extremely sensitive antennae test the ground over which it is to travel while the eyes, one at the base of each antennae, enable it to avoid light.
? When irritated, they often eject slime, sometimes to a distance of almost a foot, from a pair of glands which opens on the oral papillae.
? This slime sticks to anything but the body of the animal itself; it is used to capture flies, woodlice, termites, etc and it is a weapon of defense.
? A pair of modified appendages serve as jaws and tear the food to pieces.
? Most species are viviparous, and a single large female produce 30-40 young in a year. These young resemble the adults when born, differing chiefly in size and colour.
6. How many species belong to class Merostomata?
Answer: 5.
7. Write an article on the activity of Xiphosuran polyphemus (5 lines)
Xiphosuran is a burrowing animal and lives in the sand.
It may be active at night moving by short swimming hops, the respiratory appendages giving the necessary impetus, whilst between each two short flight the animal balances itself for a moment on the tip of its tail.
The food of xiphosuran consists of worms.
8. Meaning of extinct, fossil
Answer: The remains of an organism that no longer exists
9. Where the Subclass Eurypterida was found, what do you know about Eurypterus sp.
The Eurypterida known only from fossils from Paleozoic strata
Eurypterus sp.
There were scorpion-like in appearance, with a small cephalothorax and an abdomen of 12 segments. The anterior six of which were provided with unbranched plate-like appandages.
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