Class MerostomataThe body are protected by a hardshell, divided into a cephalothorax andabdomenBear six pair of appendages, thechelicerae, pedipalps and four pairs ofwalking legs.They live in deep water and feed onmolluscs and annelids.Considered living fossils –structurehas remained basically unchanged forthe last 300 million yearsPedipalpLimulus sp.(horseshoe crabs)
Class ChilopodaClearly defined head with a pair of antennaeand a pair of mouthparts.The elongated body consists of numeroussegments. Each segment bears a pair of similarappendages.Eyes are simple, compound or absent Carnivorous and feed mainly on insects, whichthey capture and kill using poison fangs on firstsegment after the headMaxilliped (poison claw)Lithobius sp.(centipede)
Class DiplopodaThe body segments bear two pairs oflegs each. Each segment also has glandswhich secret a foul- smelling liquidwhich protects them from attack.Most are herbivores that feed on live ordecaying vegetation. They play animportant role in the detritus food chain.Lulus, common millipede
Class Arachnida•Body are divided into cephalothorax (prosoma)and abdomen (opisthosoma)•4 pairs of walking legs n simple eyes.•No antennae, the function of antennae isperformed by numerous sensory hairs whichcover the body and appendages.•*Have a pair of chelicerae (fangs or pincers)which are often connected to a poison gland.•*Have a pair of pedipalps ( second pair ofappendages) which may used to hold food, actas sensory organ of taste or as pincers tocapture prey.•Mostly are carnivores that feed on otherarthropods especially insects, which they willdigest externally before ingesting it.Lycosa( spider)
Class Insecta Have clearly defined head,thorax, abdomen, a pair ofantennae , 3 pairs of mouthparts. 3pairs of legs each thoracic segmentwith a pair of legs), a pair ofcompound eyes and simple eyes.Adults have one or two pairs ofwings.Locusta, an insectThe life cycle of insects is characterisedby several moults. The stage between twoconsecutive moults is called an instarSome insects show incompletemetamorphosis, that is, the eggs hatchinto nymphs which resemble the adults inmost ways, except that they lack wingsand are sexually immature. After the lastmoult, the adult (imago) emerges.There are four distinct stages incomplete metamorphosis :egg larva pupa imagoThe larvae are morphologically,physiologically and behaviourally differentfrom adult.
Class CRUSTACEAThey have a cephalothrorax whereby thehead is not clearly distinct from the thorax.They have 2 pairs of antennae , at least onethree pairs of mouthparts (jaws), a pair ofcompound eyes raised on stalks.They have appendages on their abdomen aswell as on their thorax. The appendages indifferent parts of the body are specialised toperform different functions: feeding,locomotion, reproduction and sensorystructure.They lack a waterproof exoskeleton.They use gills which are outgrowths of thebody wall or limbs for gaseous exchange.Have separate sexes. The male use sspecialised appendages to transfersperm to the female. Fertile eggs maybe carried on the body. When the eggshatch, they develop into naupliuslarvae which is the characteristic larvalform of all crustaceans. The larvae gothrough a number of moults beforereaching maturity.Penaeus sp.(prawn)
Male and female cockroach(Clasper)The malecockroach hasa pair ofclaspers thatgrasp thefemale duringcopulation.The number of visible segments is higherin the male than the female. Also thefemales posterior abdomen is broaderand more rounded than the male
Reproduction system of male cockroachA pair of testes to producespermVas deferensSeminal vesiclesEjaculatory ductPenis**Accessory gland secret fluidthat is mixed with the spermbefore ejaculation.Vasdeferens
Reproduction system of female cockroachA pair of ovaries, each madeup of eight ovarioles whichproduce ova.OviductsVagina** Accessory glands secretechemical to make theootheca, an egg sac.** Spermathecal connectedto vagina, which store thesperm ejaculated from themale cockroach duringmating.
1. During mating, The tips of the abdomens are heldclose together, then a package of sperm wrappedin a protein capsule is inserted into the vagina ofthe female by means of extensible penis2. When the insect separate, the spermatophoreruptures and the sperm swim to thespermatheca.3. After mating, ova are passed down the vaginaand fertilised by the sperm in the spermatheca.4. The fertilised eggs are carried in ootheca . It iscarried to the insect for a few days before it isshed, usually in dark place.5. When the ootheca breaks afterabout six weeks, the youngnymphs emerge.**Cockroach showsHemimetabolous development(insect development in whichthere is incomplete or partialmetamorphosis, typically withsuccessive immature stagesincreasingly resembling theadult)