Transcript GROUP_1_insectsx

GROUP 1
PREENTATION
QUESTION
Discuss the physiological and behavioral
characteristics of insects that have
contributed to their success?
Definitions
O Physiological
O It is the branch in biology dealing with the functions
O
O
O
O
and activities of living organisms and their parts
including physical and chemical processes.
Behavioral
it is the action or reaction of an animal in response to
external or internal stimuli.
Insect
An insect is a small animal which has a three pairs of
legs and a body divided into head, thorax and
abdomen, some may have wings.
Physiological characteristics
O Possession of a highly adaptable exoskeleton.
O The exoskeleton is an impervious layer of wax which
prevents dessication.It is made up of chitin which
binds with other protein molecules to form a body
wall that is flexible, elastic and resists chemical and
physical attack .
O Walking and flying depend to a large extent on the
strength and flexibility of the exoskeleton, the tubular
design and chemical composition combine strength
with light weight.
O The skeleton provides protection from attack, harsh
conditions and injury and also minimizes loss of
body fluids.
Physiological characteristics
O Possession of wings and ability to fly
O The insects are the only invertebrates that
can fly.
O The power of flight has allowed insects to
escape un favorable habitats and to
colonize new habitats, sometimes at great
distances.
Continue…….
O Flying insects are at an advantage in
escaping enemies and finding mates, food
and places to lay eggs e.g the migratory
locust, Locusta migratoria (Orthoptera).
O The elasticity of the thorax enables flight
musculature which produces at least two
times more power per unit to muscle mass
hence making flying easier resulting in a
long distance fly and edurance.
Physiological characteristics
O Small size.
O there are many more niches for small
organisms than for large organisms. For
instance ,one insect could live solely on and in
the seeds of a specific plant .
O Because of the exoskeleton a small body is an
advantage. Imagine if an insect had the size of
an elephant obviously the exoskeleton would be
thicker and larger to accommodate the animal
and protect it and also would require a lot of
energy for coordination.
Continuation……….
O Small size gives them an advantage that minimal
resources are needed for survival e.g. a crumb is a
feast a dewdrop quenches thirst and a pebble
provides enough shade.
O Small size makes the insect flexible that it can hide
from predators in cracks of rocks ,with the help of
the hard exoskeleton they can burrow between
individual grains of sand .
O Small size together w the adaptations in body shape
and coloration, gives many species the ability to
blend so well with the environment that they
become virtually undetectable.
Would you recognise its an
insect
Continue…….
O Metamorphosis
O There is variation in the life style of different
stages in an insect’s life. (e.g caterpillar vs
butterfly) reduces competition for resources
within the species
The ability of insects to undergo significant
changes as they grow from immature to adult
changes promote survival , dispersal,
reproduction and reduce food competition
hemimetabolous and holometabolous reduces
competition between immature and adults.
Physiological characteristics
O Adaptation of appendages
O Mouth parts and legs have often become highly
specialized and hence are greatly varied in
different groups of insects
O Mouthparts may be adapted for taking solid food
or liquid
O Legs may be adapted for walking , jumping ,
clinging, grasping ,swimming, or digging.
O The ovipositor may be modified according to the
media into which eggs are deposited
Continue……..
O Sensory sophistication
O The sensory capabilities of insects
surpasses most other organisms.
O Insects can therefore quickly detect
predators, find mates and food.
Behavioral characteristics
O Evolutionary interactions with other
organisms
O Co-evolution leads to greater specialization
and speciation.
O Most of the flowering food crops have coevolved with the insect species, especially
the bees that pollinate them.
…………continue
O High fecundity /Large reproductive ability
O Large numbers of offspring support a large
variation for selection and evolution to act upon.
O The females produces a large number of eggs
which most of them hatch, the females in other
species contains a spermathica and only require
one mating to fertilize all the eggs she has in a
lifetime.
For example
a
single colony of Australian termites (Isoptera) can
swell to several million individuals within an earthen
an earthen mound 6-7.5m tall.
Continuation of the behavioral
characteristics……….
O Short life cycle
O Small size also permits short generation
time
O This allows many generation within a given
time for selection and evolution to take
place thereby leading to many species
O Even though insects have a short lifecycle a
process of voltinism happens whereby some
are univoltine, bivoltine, multivoltine and
semivoltine.
Behavioral characteristics
O Keen sensory perception
O Insects respond to stimuli either towards or
away from the stimuli for example attraction
of moths(Lepidoptera) to light and
avoidance of light by cockroaches
(Blattodea).
Behavioral characteristics
O Communication
O Insects communicate with other organisms of the
same specie by means of chemical, auditory and
tentile signals.
O Insects produces sounds and also hear sounds. They
make sounds to attract a mate or communicate
danger to the others. They can also hear sounds like
the Hawk moths can hear ultrasounds from bats and
take action.
O There is also the production of light and great vision.
An example is the fireflies which are biolumiscent
and produce light to communicate and attract mates.
Behavioral characteristics
O Internal systems
O Insects have a true coelom in which distinct
internal systems are all found and
accommodated without disturbing the other
O Insects have a complete digestive system
which has a foregut, midgut, hindgut,
esophagus, crop, pharynx and
proventriculus.
O Though the digestive system is a
physiological characteristics.
Internal anatomy of an insect
O Insects have nervous system which has
nociceptors that detect and transmit signals
responsible for pain sensation though there is
no consensus that insects feel pain
consciously.
O Most insects have a high trachea system
which delivers oxygen directly to the tissues
and cells making a high metabolic rate
possible .
O Circulatory system of an insect is open.
References
1.Ross H H 1996, A text book of Entomology
2nd edition New York Chapman and Hall limited
2.Meyer J R 2007 Principles of entomology
3 Snodgrass R. E 1935 ,Principles of insect
morphology. New York McGraw Hill Book Co.
Questions…
GROUP MEMBERS
1 Chimhanda Rudo S F
R164415F
2 Lunga Chapo Y
R167175R
3 Muoesi Brian T
R1610334
4 Nyakunu Trust
R1610344
5 Marufu Batsirai
R167170T
6 Tarirai Devotion
R167124D
7 Maparanyanga Shephered
R167135E
8 Mavugera Mordecai
R167154D
9 Tsiga Nigel
R1671515
10 Mudehwe Chief
R167163W
11 Chado Melody
R164434W
12 Gwat Vivian
R167140A
13 Mangwende Andrew
R164435J
14 Mangonga Simon
R167128V
15 Katurura Caroline
R169904X
16 Chikono Amanda
R169276P
17 Masesengwe Nyasha
R167129X