Kingdom Animalia
The distinguishing characteristics of kingdom Animalia
Ø Animals are multicellular and each cell is bound by a plasma membrane.
Ø Animals bodies are differentiated into tissues
Ø Animals are heterotrophic.
Ø Animals are capable
of locomotion.
Ø Animals have a nervous
system
Phyla of kingdom Animalia
Ø Phylum Annelida
Ø Phylum Arthropoda
Ø Phylum Chordata
Ø Phylum Platyhelminthes
Ø Phylum nematode (Aschelminthes)
Phylum Annelida
The word annelid is derived from a Latin word
‘’annelus’’ which means little
ring. Thus members
of this phylum are known as ringed or segmented worms. Annelida is a large
phylum comprising of rag worms,
lugworms, earthworms and leeches
The most common species
is the earth worms
General features of annelids
Ø They have a lip
like extension on the first segment above the mouth
called prostomium
Ø Most annelids have chaetae. Chaetae is chitinous hair-like structures used for locomotion.
Ø Some annelids have well developed metameric segments through the body
Ø They have bilateral
symmetrical bodies
Ø Excretion takes place in convoluted tube-like structures called nephridia found in each segment
Ø They have moist outer covering called cuticle vii. They reproduce by both asexually and sexually
Ø They have closed
circulatory system where by the blood flows
Ø They have a central nervous system with paired cerebral ganglia in which paired commissures around the
gut lead to a double ventral nerve cord
Ø They arc eucoelomates meaning that their body cavities
are lined by mesodermal tissues
in both sides.
Ø They have triploblastic bodies
Distinctive features
of annelids
Features which distinguish annelids from other animals are as follows:
Ø Most annelids have hair-like structures called chaeta or setae made
up of chitin.
Ø These are used for locomotion.
Ø They have perfect
metameric segments throughout the body.
Structure of earthworm
Ø An earthworm is an elongated, roughly cylindrical and metamerically segmented organism.
Ø Each segment contains body systems such as circulatory, nervous, excretory and digestive systems.
It has a complete digestive system
that runs through the length of its body with
both mouth and anus.
Ø The circulatory system is simple
and closed. The earthworm has a central
and peripheral nervous systems.
Ø Earthworms are hermaphrodite meaning that each individual has both male and female reproductive organs.
Advantages of annelids
Ø
Some annelids improve soil aeration
through burrowing and mixing up of soil layers.
Earthworms play very important role in improving soil aeration. Hence maintaining soil.
Fertility.
Ø
They are used for commercial
production of compost manure in the process
known as vermicomposting.
Ø
Some annelids are used as a
bait in the fishing industry Examples
of annelids used as bait include earthworms and lugworms.
Ø
They are used as source
of nutritious food for some fish and birds. They are rich in proteins
and vitamins.
Ø
Some annelids are ecological
decomposers. Hence, they contribute
to nutrient circulation because they feed on decaying organic matter.
Ø
They remove pollutants from the
soil and clean the environment by transforming organic wastes during feeding.
Ø
Faeces and urine of some annelids
have considerable value as manure
and increase soil fertility.
Ø They are used as specimens
in biological studies.
Ø
The excretory waste of some
annelids which are in the form of cast
increases sticking together of soil particles. This in turn increases
water holding capacity
of the soil.
Disadvantages or annelids
In some cases, annelids are harmful. The harmful effects
of the annelids include
the following:
Ø
Some annelids damage young roots of the growing
plants.
Ø Leeches are harmful to mammals, reptiles and fishes because they suck blood.
Ø Earthworms can increase soil porosity and aeration which may cause water loss by seepage
from the forms.
Advantages of earthworm in agriculture
Ø Earthworms help in soil formation
by barrowing process
Ø They add nutrients when they decompose or giving out waste products
from their bodies
Ø They increase soil aeration. During the process of barrowing they increase
soil porosity hence soil aeration
Ø Their burrows help rainwater to drain through
the soil more easily and prevent water logging.
Ø They drag leaves and other plants part into the soil when they feed which
adds humus content
of the soil.
Ø
They are used by fishermen to trap fish during fishing
Ø
They improve water holding
capacity of the soil
Habitat of earthworm
They live in moist soil
Mode of nutrition of earthworm They are heterotrophs (omnivorous)
Mode of reproduction of earthworm
They reproduce sexually by producing egg and sperm at
the clitellum. Fertilization is external
Organism Kingdom Phylum class Earthworm Animalia Annelida Oligochaeta
Common name is Earthworm. Classification of earthworm to class level
Phylum arthropoda
General features
of arthropods
Ø They have jointed and paired appendages that may be modified in various
ways to form structures such as antennae,
mouthparts, legs and reproductive organs.
Ø They have segmented bodies which are organized into regions called
tagmata. These regions
are the head,
thorax and abdomen
Ø They have a coelom that is reduced and confined to cavities of excretory organs and reproductive duct.
They also have another cavity called
haemocoel which is formed during
their development.
Ø They have exoskeleton made up of chitin covering their body.
Ø They have a ventral nervous
system.
Ø They have open circulatory system which is dorsally positioned.
Ø Their body plan is bilaterally symmetrical.
Ø They have compound
or simple eyes.
Distinctive features
of arthropods
Ø
They have jointed appendages
which serve different purposes such as feeding,
locomotion and sensation.
Ø They have segmented bodies organized into regions called
tagmata.
Ø
They have an exoskeleton which is made up of a chitin. The exoskeleton is usually stiff rigid or flexible.
Classes of phylum
Arthropoda
i.
Class Arachnida
ii.
Class Diplopoda
iii.
Class Insecta
iv.
Class Crustacea
v.
Class Chilopoda
Class Arachnida
Arachnids are terrestrial arthropods consisting of
animals whose bodies are divided into
two regions; prosoma and opisthosoma. In some
arachnids the two region are separated by a narrow waist like constriction. The prosoma is partly or
completely covered with a carapace
like shield. Members of this class lack antennae and the majority are carnivores which feed on other invertebrates or
small vertebrates. Others arachnids
such as ticks and some mites are ectoparasites which feeds on the blood of vertebrates.
Examples of arachnids are spiders, mites,
ticks and scorpions.
Observable Features of arachnids
Arachnids possess various unique features these features
include:
Ø They have no antennae, instead they have a pair of pedipulps which they use for defense and detection of stimuli.
Ø They have four pairs of walking legs that arc attached to the cephalothorax.
Ø They have only simple eyes used for vision while others are completely blind.
Ø Gaseous exchange in arachnids
is by means of book lungs or trachea.
Ø They lack mandibles
Structure of the spider
Economic importance of arachnids
Arachnids are both advantageous and disadvantageous to
human being and other organisms
as follows;
Advantages of arachnids
Ø Some arachnids such as mites play an important role in the formation of humus from decomposed leaf litter and wood.
Ø Many arachnids are used as food by other animals. For example, spiders
arc used as source
of food by frogs,
lizards and birds.
Ø Spiders and other arachnids teed on wide range of pests thus helping
to keep the population of pests under control.
Ø Silk from spiders can be harvested for production of useful products
such as surgical threads and bullet-proof vests.
Ø They are used in biological studies and research.
Disadvantages of arachnids
Ø Some arachnids such as scorpions can sting human beings and release their venom that cause severe
pains. The bite from some spiders
such as the black widow Latrodectus species
can cause serious health
problems in children
and even death.
Ø Some arachnids arc parasites to mammals and other vertebrates. Examples of such arachnids are ticks and
mites which usually bite humans and
other animals causing pain. They can also transmit diseases.
Ø Some arachnids destroy crops and other properties. Examples of such arachnids are mites that attack food
crops (on farm and in storage) and
timber. Observable features of spider, and ticks i. Have four pair of legs ii. Have simple eyes
iii. Body divided into two regions iv. Have poisonous sting
Adaptations of spider,
and ticks
Ø Have simple eyes for sight
Ø Have poisonous sting for protection
Ø Have legs for locomotion
Habitat
of spider and ticks
Ø They are terrestrial organisms living in rocks, roof of
the walls and in the soil
Classification of spider and ticks to class level
|
Organism |
Kingdom |
Phylum |
Class |
|
Spider |
Animalia |
Arthropoda |
Arachnida |
|
Tick |
Animalia |
Arthropoda |
Arachnida |
|
Scorpion |
Animalia |
Arthropoda |
Arachinida |
Class Diplopoda
Structure of a millipede
The body of millipede is elongated,
cylindrical and segmented. The body
consist of a series of segments whose number varies depending on the species.
The
segments contain glands
that secrete a noxious chemical
to repel predators.
Each trunk segment hears two pairs of walking legs with
exception of the segment behind
the head.
Millipedes also have a
head with one pair of antennae that help them to
detect stimuli from the
surroundings.
The head also has one pair of mouth parts that is found
in from of the head.
Most millipedes have simple eyes located above the jaws.
Such millipede have ability to see.
However, some millipedes have no eyes at all,
so that they cannot see.
Economic importance of diplopods
Diplopods are both advantageous and disadvantageous to
both plants and animals including
human being.
Advantages of diplopods
Ø Most diplopods are used as source of food to other animals including birds, reptiles and amphibians.
Ø They are also used in biological studies
and research. Since diplopods feed on
decaying plants and animal matter,
Ø They help in the recycling
of nutrients in the ecosystem.
Disadvantages of diplopods
Ø Some herbivorous millipedes can cause damage
to crops in the field.
Ø
Burrowing diplopods can cause
some damage to the roots or germinating seeds.
Adaptation of millipede
Ø They possess legs for locomotion
Ø Presence of exoskeleton which protect them from external injury
Ø They secrete a toxic fluid for protection from predators.
Ø They live in soil and they are brown blackish in colour gives them camouflage.
Ø Have one pair of antenna
for sensation
Observable features of millipede
Ø Have two pairs of legs in each segment
Ø Have cylindrical body
Ø Have one pair of
antennae
Ø Body divided in many segment
Ø Have simple eyes
Habitat of millipede They lives in
shady moist soils rich in organic matter
Common name is millipede.
Classification of millipede to class level
|
Organism |
Kingdom |
Phylum |
Class |
|
Millipede |
Animalia |
Arthropoda |
Diplopoda |
This class includes the centipedes
The structure of the centipede
Chilopods, commonly known as centipedes, have a distinctive elongated, segmented body with one pair
of legs per segment. Here's a brief description of their structure:
Body Segmentation: The
body of a centipede is divided into numerous
segments, each bearing a pair of legs. These segments are visible externally and give the centipede its
characteristic segmented appearance.
Head: At the anterior end
of the body is the head, which houses the
sensory organs, including a pair of antennae and a pair of mandibles for capturing and consuming prey.
Centipedes have well-developed
compound eyes, typically with multiple lenses,
which help them detect movement
and locate prey.
Legs: Centipedes are named
for their numerous legs, with one pair
per body segment. The number of legs varies among species but typically ranges from 15 to over 100
pairs. The legs are jointed and used
for locomotion, enabling centipedes to move swiftly across
various surfaces.
Exoskeleton: Like other
arthropods, centipedes have an exoskeleton made of chitin,
a tough, protective outer covering that provides support and protection for
the body. The exoskeleton must periodically molt as the centipede grows.
Venomous Fangs: Most
centipedes possess venom glands located
near the base of their mandibles. These glands produce venom that is injected into prey through hollow fangs, aiding in subduing
and immobilizing the centipede's prey.
General characteristics of class chilopoda
Ø
Most centipedes are nocturnal
and scurry (hide) in the surface of logs, rocks and forest floor
debris
Ø They lack waxy cuticle and therefore require moist habitats
Ø They have single
pair of legs on each segment
Ø The last pairs of
legs is modified into long sensory appendages
Ø The body has about 15 to 20
segments
Ø They are carnivorous
Ø They have one pair of antenna
Ø Most of them are terrestrial organisms
Ø Gaseous exchange is by using
tracheal system
Ø They have poison claws, which are modified legs on first
segment
Economic importance of chilopods (centipede)
Ø
Many chilopods are used as food
since they are a good source of
proteins to other animals such as shrews, toads, badgers and birds.
Ø They are used in biological studies and research.
Ø They help in the elimination of harmful insects such as ants, termites and bugs.
Ø
They have venomous claws; can
bite humans and other animals causing pain, small wounds and blisters.
Adaptations of centipedes
Ø They have segmented
body which allows
flexibility
Ø They have numerous
legs for rapid locomotion
Ø They have venomous fangs for self defense
Ø They have well-developed sensory organs, including compound eyes and antennae which help them detect
movement, locate prey, and navigate
their environment effectively.
Observable features
of centipedes
Ø They have Elongated, segmented body.
Ø They have numerous pairs of legs with one pair on each segment.
Ø They have venomous
fangs.
Ø They have visible
compound eyes and antennae.
Ø They have coloration or patterns on their exoskeleton.
Ø They have flattened body.
Habitat of centipede
Centipedes inhabit a diverse range of environments, including forests, grasslands, deserts, wetlands,
caves, urban areas, mountains, and
tropical regions, preferring moist and sheltered
habitats.
Common name is centipede.
Classification of millipede to class level
|
Organism |
Kingdom |
Phylum |
Class |
|
Centipede |
Animalia |
Arthropoda |
Chilopoda |
Class insecta
Members of class lnsecta are the most diverse and most
abundant animals on the earth. They
are found in all environments or habitats including freshwater, terrestrial and marine habitats.
Common features shared by members
of the class Insecta
Ø Insects possess three distinct body segments—head, thorax, and abdomen—each with specialized functions.
Ø Insects typically have six legs, attached to the thorax, which are used for various
forms of locomotion.
Ø Insects have one pair of antennae on their head, serving as sensory organs
for detecting environmental cues.
Ø The exoskeleton of insects, made of chitin,
provides protection and support for the body.
Ø Insects have compound eyes, consisting of numerous visual units called ommatidia, which provide
a wide field of view.
Ø Many insects have wings, specialized appendages attached to the thorax, enabling flight in most species.
Ø Insects breathe through
small openings called
spiracles, which lead to a network
of tubes known as tracheae.
Ø Metamorphosis is a common feature in insects, involving distinct developmental stages such as egg, larva,
pupa, and adult, each with unique
morphology and ecological
roles.
Examples of organisms belonging to class lnsecta include grasshoppers, butterflies, houseflies,
cockroaches, beetles, bees, ants, wasps and termites.
Distinctive features
of insects
Insects differ from other arthropods in the following ways:
Ø Their bodies are divided into three main regions or tagmata, namely
the head, thorax and abdomen.
Ø They have three pairs of jointed walking
appendages.
Ø They have a highly developed mechanism of gaseous exchange through
trachea.
Ø They have holes called spiracles located on the abdomen and joined lo the tracheal tubes which help to
ensure efficient gaseous exchange
Ø Majority have one or two pair of wings
Ø Few lack wings
for example fleas and lice.
Structure of a g1asshopper
A typical example of an organism in the class Insecta is a
grasshopper. The body of a
grasshopper is elongated and segmented. It is divided into a head, thorax and abdomen
The head of the grasshopper has a pair of antenna and
compound eyes. Each compound
eye is made up of thousands of tiny units closely
packed together.
The head also consists of three pair of mouthparts namely mandibles, They have three
pairs of legs
The body of the grasshopper is covered
by a
rigid exoskeleton
Advantages of insects
Insects are both advantageous and disadvantageous to humans and other organisms.
Ø
They are used for production of
various substances. For example,
honey bees produce honey, wax and bee venom silk worms produce silk that can be used for commercial purpose.
Ø
They are used in biological
control of pests. Insects have been used
effectively as predators to kill or control pests. For example, lady beetles are used to kill aphids. Aphids arc the insect pests that transmit viruses
to plants.
Ø
Insects such as bees and butterflies arc useful in agriculture as they act as
pollinators. Many plants depend on insects for
pollination.
Ø
They are used in scientific
research particularly in fields of physiology,
genetics and evolution. The fruit flies (Drosophila melanogaster are among
the insects used for this purpose.
Ø
Some insects are used in the
production or medicine. Such insects
include blister beetles that produce cantharidin which is used for treatment
of urine genital diseases.
Ø
Many insects are used as food, they are a good source
of proteins for human beings
and other animals. Examples or such insects include
winged termites, edible grasshoppers, locusts, and cockroaches, larvae of beetles,
butterflies and moths.
Ø
Some insects are scavengers and
feed on rotten or decayed materials hence helping in reducing rubbish and ensuring
nutrient recycling in the ecosystem. Examples or such insects arc cockroaches.
Ø
Some insects improve aeration
and soil fertility. For example, termites breakdown
plant tissues thus improving soil facility
Disadvantages of insects
Ø
Some insects such as wasps and
bees can cause painful bites and stings.
Stinging insects that live in colonies can cause significant injury
and even death.
Ø
Some insects are vectors of
animal and plant diseases. For example, mosquitoes carry Plasmodium spp. which cause malaria. Tsetse flies
carry Trypanosoma spp. a parasite which cause sleeping sickness to human beings. In addition, white flies carry tomato yellow
leaf curl virus which cause chlorosis in plants.
Ø
Some insects destroy trees and
crops. Examples of such insects include locusts and the caterpillars.
Ø
Some insects are ectoparasites
of mammals. For examples jiggers and
bedbugs which tend to suck blood
from their hosts.
Ø
Some insects destroy human
properties. Example cockroaches which
spoil food. termites, beetle and carpenter bee that cat wooden furniture and moth larvae that feed
on carpets and clothes.
Observable features of class insecta
Ø Have one pair of antennae
Ø Have jointed legs
Ø Have pair of wings
Ø Have compound eyes
Ø Body divided into three parts
Adaptations of Class Insecta
Ø Have antennae
for sensation
Ø Have legs for locomotion
Ø Have wings for flying
Ø Have compound
eyes for maximum sighting
Ø Have abdomen for reproduction and respiration
|
Organism |
Kingdom |
Phylum |
Class |
|
Housefly |
Animalia |
Arthropoda |
Insecta |
|
Cockroach |
Animalia |
Arthropoda |
Insecta |
|
Beetle |
Animalia |
Arthropoda |
Insecta |
Phylum Chordata
Phylum Chordata encompasses a diverse group of animals sharing
key characteristics including a notochord, dorsal
nerve cord, pharyngeal slits,
and post-anal tail at some point in their life cycle.
General features of chordates
Chordates possess the following features:
ØThey are triploblastic animals.
ØThey are coelomate animals.
ØTheir
bodies are metamerically segmented and bilateral symmetry.
ØSome are homotherms while some are piokiotherms
ØMost
chordates have a ventral heart. (l) Most chordates have a closed
circulatory system.
ØMost have endoskeletons made up
of bones and cartilages
ØSome
chordates have central nervous system made up of the well-developed brain and a spinal cord.
ØThey occupy
both terrestrial and aquatic
habitats.
ØSome
chordates are viviparous in which their young develop inside the body while others are oviparous as their young develop
outside the body
ØMost
chordates have a complete digestive system with two openings, the mouth and anus.
ØMost
chordates have segmented muscle blocks called
myotomes, one muscle
block on either
side of the body.
Distinctive features
of chordates
Chordates have unique features that differentiate them
from other animals.
They have the following features at some stages of embryological development:
ØA notochord.
ØPharyngeal pouches
or gill slits.
ØPost-anal tail.
ØA dorsal hollow tubular
nerve cord.
Classes of phylum
chordata
The classes of Phylum
Chordata include:
1.
Class Mammalia (Mammals)
2.
Class Aves (Birds)
3.
Class Reptilia (Reptiles)
4.
Class Amphibia (Amphibians)
5.
Class Chondrichthyes (Cartilaginous fishes)
6.
Osteichthyes(bony fish)
Class Osteichthyes
This class comprises of the bony fish. Their skeleton
is made up of hard bones instead of cartilage.
Examples of bony fish include tuna, tilapia, Nile perch, herring, butterfly fish and catfish
Distinctive features of bony
fish
The following features differentiate bony fish from other
chordates:
Ø They have four pairs of visceral clefts as their gill openings. These are covered
by an operculum.
Ø Most of bony fish have swim or air bladder which provides them buoyancy
during swimming.
Ø Most have a bony endoskeleton and their skin is covered by glands
producing mucus that make them slippery.
Ø Most have symmetrical or homocercal caudal fins. This means that their caudal
fins can be divided
into equal parts.
Ø They have terminal mouth.
Structure of a Tilapia
Body Shape: Tilapia typically have a laterally compressed body with a somewhat oval or elongated shape. This
streamlined body allows them to move efficiently through
water.
Fins: They have several fins, including dorsal fins (one or two), anal fin, pelvic fins, and caudal fin (tail
fin). These fins provide stability and control
during swimming.
Scales: Tilapia have overlapping scales covering their body, which provide
protection against predators and environmental factors.
Mouth and Teeth: Tilapia have a terminal mouth, meaning it is located at the front of the head. They
possess specialized teeth adapted for their omnivorous diet, which may include both plant matter and small invertebrates.
Gills: Like other fish, tilapia have
gills located on the sides of their head,
which are responsible for extracting oxygen from the water and removing carbon dioxide.
Economic importance of bony fish
Most bony fish have both advantages and disadvantages to humans
and other animals.
Advantages of bony fish
Ø Most bony fish are rich in protein,
hence, they are used as
food to human
and other animals.
Ø They are also source of income to fishing
communities. Industrially processed
fish products such as bones can be transformed
into usable goods such as chicken
feed.
Ø Oil produced from the fish are also useful as medicine. Some bony fish are used for ornamental purpose.
Additionally some bony fish are used in biological studies and research.
Disadvantages of bony fish
Ø Sting from some bony fish such as stonefish can cause pain,
swelling, necrosis and even death.
Ø Shocks from electric eels and electric catfish can cause injury or death
due to drowning.
Ø Also, some exotic bony fish when introduced into a new habitat can cause extinction of endemic fauna due
to competition and predation.
Adaptations of tilapia
i. It has tail for swimming
ii. Possess gills for gaseous exchange
iii. It has pair of eyes and nostrils
for sensitivity
iv. Cycloid scales pointed backward to support movement during swimming
v.
Possess swim bladder for buoyancy maintenance
Observable features of tilapia
Ø Tilapia typically have an oval or elongated body shape, with a laterally compressed profile.
Ø They have several fins, including dorsal fins (one or two), anal fin, pelvic fins, and caudal
fin (tail fin).
Ø Tilapia have overlapping scales covering their body, which may vary in color and pattern.
Ø Tilapia have a terminal mouth, usually with visible teeth adapted
for their omnivorous diet.
Ø They have prominent eyes located on the sides of their head, providing a wide field of vision.
Ø Tilapia have gills visible on the sides of their head, which are used for breathing underwater.
Ø Tilapia can vary in size depending on the species
and age, ranging from a few inches to over
a foot in length.
Habitat of tilapia
They are living in water (aquatic organism) Mode of reproduction of tilapia fish
Reproduce sexually by external fertilization
Classification of tilapia fish to class level
|
Organism |
Kingdom |
Phylum |
Class |
|
Tilapia fish |
Animalia |
Chordata |
Osteichthyes |
Class amphibia
The term Amphibia comes from two Greek words
"amphi" meaning
"both" and "bios" which means "life". Therefore. Amphibia literally mean double life. This
is due to the fact that amphibians live both in water and on land.
Most amphibians spend their life partly in aquatic
environment and partly
in terrestrial environment.
They have two pairs of pentadactyl limbs for locomotion
except caecilians which are limbless.
The forelimbs of some amphibian have less musculature
while the hind limbs of frogs and
toads arc long with powerful muscles for jumping.
Distinctive features of amphibians
Amphibians have the following unique features that
differentiate them from other chordates:
Ø They have protruding eyes for wide visibility of prey.
Ø
Amphibian eggs have a jelly
structure which is prone to dehydration when exposed
to air.
Ø
During the larval stage
amphibians use gills for gaseous exchange. In
adult stage, amphibian
use their skins when they are in water and lungs when they are on land.
Ø
They have moist skin and most
occupy both water and land environments.
Structure of a frog and a toad
Amphibians are characterized by several distinctive anatomical features:
Body: Amphibians typically have a moist, permeable skin, lacking scales, feathers, or hair. Their
skin serves various functions,
including respiration, water absorption, and protection against predators and pathogens.
Limbs: Most amphibians have four limbs, each with digits (fingers and toes). The limbs are adapted
for locomotion on land and may be webbed
in aquatic species.
Skin Glands: Amphibians possess specialized skin glands that secrete mucus, which helps keep their
skin moist and aids in respiration and thermoregulation.
Eyes: They have large, protruding eyes with well-developed vision, adapted for both terrestrial and
aquatic environments. Many
amphibians have a nictitating membrane, a transparent eyelid that protects
the eyes underwater.
Ears: Amphibians have tympanic membranes
(eardrums) located on the sides of their head, which detect
sound vibrations and facilitate hearing.
Respiratory System: Amphibians typically have three methods of respiration: lungs, skin, and buccal pumping. While some species rely primarily on lungs for
breathing, others supplement oxygen
intake through cutaneous respiration, absorbing oxygen directly through their skin. Buccal pumping involves rhythmic movements
of the throat to force air into the lungs.
Heart and Circulatory
System: Amphibians have a three- chambered heart (two atria and one
ventricle), which partially separates
oxygenated and deoxygenated blood. This allows for some separation of oxygen-rich and oxygen-poor blood, but less efficient than the four-chambered heart of mammals and birds.
Reproductive Organs: Amphibians typically have external fertilization, with males and females releasing eggs and sperm into the water. Some species undergo complex
reproductive behaviors, such as
courtship displays or parental care of eggs and larvae.
These structural adaptations enable amphibians to thrive in diverse habitats, including aquatic
environments during their larval
stage and terrestrial habitats as adults. However, amphibians are particularly sensitive to environmental changes, including
pollution, habitat destruction, and climate change, making them vulnerable to population declines and extinction threats.
Economic
importance of amphibians Advantages of amphibians
Ø Some amphibians arc source of food to humans and other organisms such
as snakes and birds.
Ø They are also used in biological studies and research. For example, frogs and toad are dissected in school
laboratories to study various body systems.
Ø Since they eat flies, they help in eliminating disease vectors such
as houseflies.
Ø In addition, some amphibians have unique features that attract researchers and tourists, hence act as the
source of income. The Kihansi Spray
Toad (Nectophrynoides asperginis) for
example has unique biological feature of giving birth to live Youngs.
Ø In the amazon basin, secretions from some amphibians are used by natives
to produce toxin darts used for hunting
purpose.
Disadvantages of amphibians
Ø
During breeding period, some amphibians such as male frogs and toads
make loud noise thus annoying people living in that environment.
Ø
They also contribute to water
pollution by laying their eggs on the surface
of water. Some frogs, toads and newts produce toxins which cause skin irritation and severe symptoms if ingested Toxins from cane toads can cause seizures,
cardiac effects and even death.
Habitat of the frog
They are found normally in damp situations on grass near
water, damp ditches and swimming
in ponds or streams.
Common name is frog.
Scientific name of frog is Rana temporaria.
Mode of
reproduction of frog
They reproduce sexually by external
fertilization
Class reptilia
Reptiles are among a diverse group of egg-laying
vertebrates. Their bodies are covered
with scales or scutes, Reptiles include animals
such as crocodiles, alligators, chameleons, tortoises, snakes and lizards.
They undergo internal
fertilization and their fertilized yolky eggs are laid on land. However, some reptiles
such as snakes are oviparous. This
means they lay eggs which remains in the mothers’ body until they are ready
to hatch.
Reptiles are found in diverse habitats such as deserts,
mountains, rocks, tree tops and in
water. They are mostly terrestrial with few
aquatic members such as crocodiles, turtles and terrapins. They are ectothermic (poikilotherms)
vertebrates, implying that their body
temperature fluctuates according to the change in environmental temperature. Most reptiles have two pairs of pentadactyl limbs. Some members such us
snakes and some lizards are limbless.
Distinctive features of reptiles
Reptiles possess the following distinctive features:
Ø They have dry skin covered
with horny scales
or scutes.
Ø
Their eyes are located at the
front part of the head to facilitate binocular
vision. Some reptiles can move each eye independently. This helps to increase their visibility hence locating their
food and escaping from predators.
Ø
They lay soil shelled eggs
called amniotic eggs which protect the embryo
from drying out. The eggs have yolk which nourishes the embryo and enables
it to develop outside the water environment.
Ø
All reptiles have a
three-chambered heart except crocodiles which
have a four-chambered heart.
Ø Most have clawed feet.
Structure of reptiles
The following is the description of the structure of all reptiles
Body: Reptiles have a tough, scaly skin that helps prevent water loss and provides
protection against predators
and environmental hazards. Unlike amphibians, reptiles have
dry, keratinized skin without glands
for respiration.
Limbs: Most reptiles have well-developed limbs, with five toes on each foot (pentadactyl). Some species
have adapted to a limbless or reduced-limb form,
such as snakes
and certain lizards.
Eyes: Reptiles have well-developed eyes with distinct pupils, adapted for various activities such as hunting,
navigation, and communication. Many
reptiles have eyelids, while others have a
transparent spectacle or a fixed eye cover.
Scales: Reptiles have scales covering their body, which are composed of keratin. These scales provide
protection, support, and aid in reducing
water loss.
The structure of the lizard
Economic importance of reptiles
Reptiles are both advantageous and disadvantageous to
humans and other organisms as follows:
Advantages of reptiles
Ø
Reptiles are used by other
animals as source of food. For example, birds
eat reptiles such as snakes, lizards and chameleons. Some reptiles such as crocodiles, turtles and snakes are a
source of human food in some communities.
Ø
Some reptiles also provide
valuable skin used in making different products.
For example, the crocodile skin is used in making belts, shoes and handbags.
Ø
Since reptiles eat small
insects they help to reduce harmful insects
in the environment or ecosystem. For example, lizards
feed on mosquitoes and cockroaches, hence reduce their
population in the environment.
Ø
Furthermore, some reptiles or their products
are used for ornamental purposes. For example, tortoises are used for decoration in homes.
Ø Tortoise shells are used to make combs,
ornaments and traditional
Disadvantages of reptiles
Ø
Some reptiles such as
crocodiles can attack livestock and humans causing serious
injuries or death.
Ø
A bite from venomous snakes can
also cause serious health problems or death to humans and other
organisms.
Class mammalia
The study of
mammals is called mammology
Mammalia contains a small number of species but it is probably more successful than other animals
There are terrestrial, aquatic,
and aerial mammals;
oviparous, ovoviviparous and viviparous mammals.
General characteristics of mammals
Ø Body covered with hair.
Ø They have integument with sweat, scent, sebaceous, and mammary glands.
Ø They have skull with two occipital condyles and secondary bony palate;
middle ear with three ossicles
(malleus, incus, stapes).
Ø They have seven cervical
vertebrae; pelvic bones fused
Ø They have mouth with diphyodont teeth (milk, or deciduous, teeth replaced by a permanent set); teeth
heterodont in most (varying in structure and function)
Ø They have movable
eyelids and fleshy
external ears (pinnae).
Ø They have circulatory system of a four chambered
heart
Ø They have respiratory system of lungs with alveoli
Ø They have muscular
diaphragm which separates thoracic and abdominal cavities
Ø
The brain highly developed, especially cerebrum
Ø
They are endothermic
Ø They have separate
sexes; reproductive organs of a penis, testes
(usually in a scrotum),ovaries, oviducts
and vagina
Ø They undergo Internal fertilization; eggs develop in a uterus with placental attachment
Ø
The young are nourished by milk from mammary
glands
Structure of mammals
The general structure of mammals encompasses several observable features:
Body Covering: Mammals typically have a covering of fur or hair on their skin, providing insulation, protection, and often camouflage. However, some mammals, such as
whales and dolphins, may lack fur and
have a smooth, streamlined body adapted for aquatic life.
Limbs: Most mammals have four limbs, each ending in digits (fingers or toes). Limb structure varies
depending on the mammal's mode of
locomotion; for example, terrestrial mammals
generally have limbs positioned directly beneath their body, while arboreal
mammals may have grasping appendages for climbing.
Mammary Glands: All mammals possess mammary glands, specialized structures that produce milk to nourish their young. These glands are typically located on the
ventral side of the body and are
present in both males and females, although they are primarily functional in females during lactation.
Teeth: Mammals have a variety of tooth shapes and arrangements adapted to their diet and feeding habits.
They typically have heterodont
dentition, meaning they have different types of teeth (incisors, canines, premolars, and molars) for biting, tearing,
and grinding food.
Ears: Mammals have well-developed ears with external
structures such as pinnae (ear flaps) that help capture and direct sound waves to the inner ear. They also
have middle and inner ear structures responsible for hearing and balance.
Eyes: Mammals generally have well-developed eyes with complex structures, including a lens,
retina, and iris. Most mammals are
capable of color vision, although the degree of color perception varies
among species.
Warm-bloodedness
(Endothermy): Mammals regulate their body temperature internally, maintaining a
relatively constant temperature
independent of their surroundings. This adaptation enables mammals to inhabit diverse environments and engage in various
activities regardless of external conditions.
Reproductive Organs: Mammals have internal fertilization and give birth to live young (with few exceptions, such as monotremes). Females typically have a
uterus and a pair of ovaries, while males have testes that produce sperm.
The diagram
of the digestive system of the rat
The diagram of the female reproductive system of the rat
The diagram of the male reproductive system of the rat
Class aves
The study
of birds is called
ornithology
Birds
are traditionally classified as members of the class Aves (from Latin word avis = bird).
The single
unique feature of birds is possession of feathers. No other living vertebrate group has feathers
Characteristics of bird
Ø Body spindle shaped, with four divisions: head, neck, trunk, and tail
Ø
They have four limbs but the forelimbs modified
for flying
Ø
They have circulatory system of 4-chambered heart.
Ø
They are endothermic (Homoeothermic).
Ø
Gaseous exchange is by lungs,
with thin air sacs
Ø Excretory system of metanephric kidney;
ureters open into cloaca; no bladder; semisolid urine;
Ø
Uric acid is the main nitrogenous waste.
Ø Sexes are separate; testes paired, with the vas deferens opening into the cloaca; females with functional
left ovary and oviduct only,
copulatory organ (penis) is present only in few birds e.g. ducks, geese, and paleognathids.
Ø
Fertilization is internal
The similarities between birds and reptiles
1.
Both have scales creates a
waterproof barrier that helps prevent dehydration in dry air
2.
Both lay eggs – shelled eggs on land (amniotes)
The differences between birds and reptiles
1.
Birds have feathers, reptiles
do not have feathers.
2.
Birds have wings allowing
them to fly while reptiles have lack wings
3.
Reptiles are cold blooded
or ectothermic; while
birds are warm blooded or endothermic.
4.
Birds have hollow bones making them lighter
& able to fly while reptiles
have solid, dense bones.
Adaptations of birds for flight
Ø They have feathers
which are used for flight
Ø They have no teeth, urinary
bladder, no penis in
most birds and have only one ovary
of which all of them help
to reduce body weight
Ø They have pneumatic (air filled) bones which help to reduce body weight
Ø They have enlarged sternum where the flight
muscles are attached
Ø The have long neck for balance
Ø They have stream lined body to reduce
air resistance
Quill feather
Quills are
specialized features found in certain mammals,
particularly porcupines and hedgehogs, that serve primarily as a defensive mechanism. Here's a description of their structure
and functioning:
Describe the structure
and functioning of the quill feather
Structure:
Ø Composition: Quills are
modified hairs composed of keratin, the same
protein found in human hair and nails, but they are highly specialized for defense.
Ø Shape and Size: Quills vary in length and thickness depending on the species and individual. They
typically have a sharp, pointed tip and
a tapered shape, with a hollow, tubular structure.
Ø Distribution: Quills are densely packed in clusters or patches on specific regions of the animal's body,
such as the back, flanks, and tail.
In porcupines, they can cover most of the animal's dorsal surface, while in hedgehogs, they are
interspersed among regular fur.
Functioning:
Defense
Mechanism: The primary function of quills is
defense against predators. When
threatened, the animal erects its quills by
muscular contraction, making them stand upright and increasing their visibility and effectiveness as a deterrent.
Puncture
and Embedding: Quills have sharp, barbed tips that can puncture the skin of predators upon
contact. Once embedded, the barbs
make removal difficult and painful, increasing the likelihood of injury and discouraging further aggression.
Warning
Signals: Quills may also serve as visual warning signals to potential predators, indicating
that the animal is armed and dangerous. Brightly colored or contrasting quills can enhance
this warning effect, alerting predators to the potential consequences of attacking.
Behavioral
Display: In addition to passive defense, some animals may engage in active defensive
behaviors, such as rattling or
vibrating their quills, to further deter predators. This behavior amplifies the visual and auditory signals
associated with the quills, increasing their effectiveness as a deterrent.
Overall, the
structure and functioning of quills represent an effective adaptation for defense in certain mammalian species, providing both passive protection through
physical deterrence and active warning
signals to potential
predators.
