Population dispersion

Dispersion is the pattern of spacing among the individuals within the population. Basically there are three patterns.

-          Clumped dispersion

-          Uniform(regular) dispersion

-          Random dispersion

Clumped

·         Commonest pattern that can observed in populations.

·         Individuals are bunched into groups within the population.

·         This is mainly results from the response to the unevenly distributed resources in their environment.

·         Also there are positive interactions between the individuals.

·         This supplies many advantages to the population such as protection from predators, reproduce and increase the population size and decrease the energetic cost of moving to do work.

Uniform

·         Individuals are uniformly spaced within the population.

·         Mainly results from the competition for resources.

·         Therefore there are aggressive interactions between the neighbours.

Random

·         Individuals are randomly spaced within the community.

·         Not that much common in nature.

·         This occurs as there are no strong interactions between the individuals.

·         They show neutral interactions.

Moulting and cuticle formation of insects

Hormones such as Ecdysone and bursicon play an important role during the events in moulting.

Apolysis

·         Epidermal cells divide and change their shape.

·         These cells separate from the inner surface of the old endocuticle and leave out the sub-cuticular space.

·         This space is consisting of moulting fluid, proteinase and chitinase.

·         These enzymes are inactive in this stage.

Formation of the epicuticle

·         Cuticulin is deposited below the moulting fluid and above the epidermis.

·         This forms the new Cuticulin layer.

·         Inner protein epicuticle is deposited under the Cuticulin layer.

Deposition of new procuticle

·         Deposition of procuticle occurs beneath the Cuticulin layer.

·         After the deposition enzymes in the moulting fluid activate and digest the old endocuticle.

·         Only a thin layer of the old endocuticle is left out.

·         This layer is called as Ecdysial membrane. These lines are located in the median lines of head and thorax.

·         Weak lines appear along this Ecdysial layer.

·         Wax secretion occurs on to the surface of the new cuticle.

Ecdysis

·         Moulting fluid and digested old endocuticle are absorbed.

·         Intake of the air and muscular contractions cause the insect’s body to swell.

·         This leads the old exoskeleton to split open along the weak lines.

·         Insect draws itself out.

·         All parts of the old cuticle are shed.

·         This old cuticle is called as cast skin.

Expansion of the new procuticle

·         New cuticle is soft and pale.

·         At this moment new procuticle expands before it hardens.

Hardening and darkening of cuticle

·         Hardening of the cuticle is known as sclerotization.

·         This forms sclerites which are rigid plates of exoskeleton.

·         It also darkens the cuticle. This is known as tanning.

Deposition of the new endocuticle

·         New endocuticle deposits after the moulting and tanning.

Orientation of insect head: Prognathous, Hypognathous and Opisthognathous

·         Three types of orientation.

                                i.            Prognathous: orientated horizontally. Mouth parts are pointed forward.

                              ii.            Hypognathous: orientated vertically. Mouth parts are pointed down.

                            iii.            Opisthognathous: orientated obliquely. Mouthparts are pointed backward.

Prognathous

·         Mouthparts are pointing forward.

·         Mouthparts are anterior in position.

·         Long axis is horizontal.

·         Mostly carnivore insects have this type of orientation.

·         Ex: Stick insect

Hypognathous

·         Mouthparts are pointing downward.

·         Mouthparts are ventral.

·         Long axis is vertical.

·         Mostly herbivore insects contain this type.

·         Ex: Grasshopper.

Opisthognathous

·         Mouthparts are pointing backward.

·         Mouthparts are directed down between coxae of legs.

·         This is known as proboscis.

·         Long axis is horizontal.

·         Ex: Plant sucking bugs.

Comparative anatomy of the skulls of primates

Loris- Loris spp

• As the brain is small, brain case is smaller than the other primates.
• Well developed supra orbital crest is present.
• Post orbital bar is also completed.
• Tympanic bulla is reduced.
• Comparatively short face.
• Eyes are forwardly directed and large.
• All teeth are pointed.
• Incisors in upper jaw are small.
• Dental formula:- 2/2, 1/1, 3/3, 3/3

Gorilla- Gorilla gorilla

• Brain case is quite smaller comparing to the whole skull.
• Low brain capacity comparative to the other Anthropoides.
• Flat supra occipital bone.
• Supra orbital bone is prominent.
• Supra occipital, supra orbital and temporal crest are well developed for a strong muscle attachment.
• Gorilla is a carnivore animal. Therefore the canines are much elongated and sharp.
• Males have larger canines than the female.
• Dental arch is rectangular.
• Dental formula is 2/2, 1/1, 2/2, 3/3

Orang Utang- Pongo spp

• Brain case is smaller comparative to the whole skull.
• Rounded supra occipital bone.
• Supra orbital ridges are not much prominent as in gorilla.
• Supra occipital and temporal crests are well developed.
• Males have large canines.
• Molars are bilophodont.
• Dental formula:- 2/2, 1/1,2/2,3/3

Chimpanzee- Pan troglodyteq

• Brain case is not smaller comparing to the whole skull.
• Therefore the brain capacity is high.
• Skull surface is smooth and rounded.
• Supra occipital and temporal crests are absent.
• Snout is comparatively long.
• Dental arch is U shaped.
• Males have large canines.
• Dental formula:- 2/2, 1/1, 2/2, 3/3

Human- Homo sapiens sapiens

• Highest brain capacity is shown.
• Smooth and rounded skull.
• Chin is present.
• Flat facial area.
• Supra orbital ridges are much reduced.
• Deeply downward foramen magnum.
• Dental arch is U shaped.
• Canines are small.
• Dental formula:- 2/2, 1/1, 2/2, 3/3

Insect Orders

Order Orthoptera

Cricket

Grasshopper

 Order Isoptera

 Odontotermes sp.(Termites)

Order Dermaptera

 Forficula sp.(Ear wig)

 Order Hemiptera

Sub order Heteroptera

 Nezara sp.

Sub order Homoptera

Aphis sp.

Order Hymenoptera

Vespa sp.(Wasp)

Ants

Order Lepidoptera

Moth

Butterfly

 Order Coleoptera

Oryctus rhinoceros (Coconut Black Beetle)

Rhuncophorus sp.(Red Palm Weevil)

 Order Phasmatoidea

Carausius sp.(Stick insect)

Phyllium sp.(Leaf insect)

 Order Mantodea

Hierodula sp.(Mantis)

Order Odonata

Libellago sp.(Damselfly)

Macrogomphus sp.(Dragonfly)

Order Thysanoptera

Thrips sp.

Order Phthiraptera

Pediculus humanus(head louse)

 Order Siphonaptera

Ctenocephalides sp.(Flea)

Order Diptera

Musca domestica

Order Blattodea

Periplaneta americana(Cockroach)

Order Thysanura

Lepisma Sp.(Silver fish)

Animal diversity

Here's a great site for almost everything you want to know about animals. It includes pictures, classification as well as information.
http://animaldiversity.ummz.umich.edu/site/index.html