Animal Kingdom

In some animals, the body is externally as well as internally divided into segments with a serial repetition of atleast some organs. This is called Metamerism. In simple words, metamerism is the condition of being constructed of a linear series of repeating parts. For example, in earthworm the body shows metamerism.

Metagenesis is the reproduction cycle of an organism alternating between sexual and asexual mode.

Metamorphosis is the process by which animals like insects, amphibians and a few aquatic animals, undergo extreme and rapid physical changes after birth.

Interstitial cells can differentiate to perform different functions. They are the totipotent cells of cnidaria. They are capable of forming any type of specialized cells.

Choanocytes are the cells found in porifera and are present in the spongocoel and the canals. They are associated with the filtration.

Gastrodermis cells and nematocytes are found in hydra.

Amphibians have two chambered heart while reptiles have three. The only exception among reptiles is crocodile as it has a 4-chambered heart. Mammals and birds also have a 4-chambered heart.

Chameleon and turtle have non-grandular skin. They belong to class reptila which possess dry and non-glandular skin. This helps them hold the moisture inside and help them survive in the dry surroundings.

Frog, pigeon and tiger possess modifications in their skin according to adaptations in their respective habitats.

Birds and mammal are warm-blooded. This helps them maintain a constant body temperature in different weather conditions.

Pigmented skin is present in Mammals not in birds.

Pneumatic bones are present in birds which help birds to have a light body and help in flight.

Viviparity is a characteristic of mammals as they give birth to young one but birds are oviparous which means they lay eggs.

Monkey, Chimpanzee, Man belong to a single taxonomic group i.e. Mammalia as all of them have mammary glands to produce milk, 2 pairs of limbs, viviparity, hairy skin, external ears.

Cuttle fish belongs to Phylum-Mollusca, Jellyfish belongs to Phylum-Cnidaria, Silverfish belongs to Phylum-Arthropoda, Dogfish belongs to Phylum-Chordata, Starfish belongs to Phylum-Echinodermata

Bat is also a mammal, pigeon is ave and butterfly is an insect.

Silkworm belongs to Phylum-Arthropoda, Tapeworm belongs to Phylum-Platyhelminthes, Earthworm belongs to Phylum-Annelida.

The incorrect statement is: Fasciola is a pseudocoelomate animal. This is because Fasciola doesn’t possess a body cavity which makes it acoelomate.

The incorrect statement is: In cockroaches and prawns excretion of waste material occurs through malpighian tubules.

This is because cockroaches excrete the waste material through malpighian tubules but prawns excrete the waste material through green glands.

Platypus are oviparous i.e. they lay eggs. They are primitive mammals which show many characteristics of reptiles such as oviparity.

Bat, elephant, whale all are viviparous i.e. they give birth to young ones.

Python is a non-poisonous snake. Cobra, viper and krait are highly poisonous snakes.

Pheretima possesses organ system level of organization. Fasciola possesses organ level organization. Spongilla possesses cellular aggregate level organization. Obelia possesses tissue level organization

When body cavity is not completely lined by the mesoderm instead it is present in the form of scattered pouches, in between ectoderm and endoderm, this type of body cavity called pseudocoelomate, e.g., roundworm.

The animals in which coelom is completely absent are called acoelomates, e.g., flatworms

Animals with body cavity lined by mesoderm and hence have true coelom, are called coelomates. E.g., annelids

The animals in which body cavity is filled with haemolymph, are called haemocoelo mates e.g., arthropods

Poriferas form a complex system of pores and canals called canal system which helps in regulating the flow of water within them. E.g. Sycon.

Aschelminthes possess jointed appendages. E.g. Ascaris.

Annelidans possess metameric segmentation in body. E.g. earthworm.

Arthropodans possess jointed appendages in each segment of their body. E.g. Cockroaches

Echinoderms possess water vascular system or ambulacral system E.g. starfish

In the phylum Echinodermata, the radial symmetry is exhibited by the adult while the bilateral symmetry is exhibited by the larva.

Radial symmetry is mainly the symmetry about a central axis while the bilateral symmetry is the property of dividing into symmetrically equal halves on either side of the unique plane.

In aves, air sacs and pneumatic bones (Bones which are hollow and filled with air) are present. Pneumatic bones make their body light weight and facilitate the flying and air sacs are helpful in respiration and buoyancy.

The phenomenon of alteration of generations between sexual and asexual mode of reproduction is called metagenesis. This phenomenon is exhibited by Obelia in which polyps produce medusae asexually while medusa produces polyp sexually.

In aves, besides pneumatic bones, feathers are also helpful in making the body weigh lighter and help in flight.

Cyclostomes possess sucking and circular mouth without jaws. Since their mouth is circular and lacks jaws, they are also called agnathans.

Examples – Hellish, lampreys, etc.

Placoid scales are the tiny tough scales that cover the skin. Trygon, Pritis are the examples of the animals possessing the placoid scales.

Cycloid scales are characterized by having a smooth outer margin. Catla, Clarias are the examples of animals possessing the cycloid scales.

To adapt to the terrestrial mode of life, reptiles require the following modifications:

• Internal fertilization (makes the chances of the survival of young ones better)

• The body is covered with dry and cornified skin and epidermal scales.

In multicellular lower organisms the shape of body is maintained by certain biological materials like chitin and calcium substances.Chitinous exoskeleton covers the body of cockroach (Arthropods) and calcareous shell covers the body of Pila (Molluscs).

Radula is a special structure in molluscs which is used to scrape and scratch the food and to create depression in rocks which molluscs use as their habitat.

The phenomenon of production and emission of light by an organism as a result of chemical reaction during which chemical energy is converted to light energy is called bioluminescence.

Members of the phylum ctenophores like Ctenoplana, Velamen, Beroe, etc.

a. Cold blooded animal: Frog (Amphibians)

Cold blooded animals can’t keep their body temperature constant in accordance with the surroundings.

b. Warm blooded animal: Humans (Mammals)

Warm blooded animals can keep their body temperature constant in accordance with the surroundings.

c. Animal possessing dry and cornified skin: Lizard (Reptiles)

Such skin helps reptile to hold the moisture inside and helps them survive in dry areas

d. Dioecious animal: Ascaris (Aschelminthes)

Ascaris are worms which are dioecious. Dioecious means the male and female reproductive organs are held by different individuals just like in humans.

a. Round worm: Ascaris

b. Fish possessing poison sting: Trygon

c. A limbless reptile/ amphibian: reptile – Snake, Amphibian – Ichthyophis

d. An oviparous mammal: Duck-billed platypus

a. Blood-filled cavity in arthropods: Haemocoel

Explanation: Haemocoel is the blood-filled cavity in arthropods containing haemolymph

b. Free-floating form of cnidaria: Medusa

Explanation:

Medusa is a form in cnidarians in which the body is shaped like an umbrella which can float freely in sed water.

c. Stinging organ of jelly fishes: Nematocyst

Explanation:

Nematocytes are capsules of specialized cells in cnidarians which act as a paralyzing sting.

d. Lateral appendages in aquatic annelids: Parapodia

Explanation:

Parapodia are the paired lateral outgrowth in annelids which are not joint and bearing chaetae.

a. Octopus – Tentacles

Explanation:

Tentacles of octopus are its appendages which help it to grasp food and for locomotion.

b. Crocodile – Limbs

Explanation:

Limbs in crocodiles are used for locomotion and swimming.

c. Catla – Fins

Explanation:

Fins in Catla are used for locomotion and used to generate optimum thrust and control the subsequent motion.

d. Ctenoplana – Comb plates

Explanation:

Comb plates in Ctenoplana are locomotory organs formed by strong cilia with fused bases.

a. Open circulatory system and closed circulatory system

b. Oviparous and viviparous characteristic

c. Direct and Indirect development

In radial symmetry, body of an individual can be divided into equal halves by any plans passing through the longitudinal axis.

In bilateral symmetry, body can be divided into two equal halves when the plane passes through the median longitudinal axis.

Radial symmetry: Coelentrates, Ctenophores, Echinoderms

Bilateral symmetry: Annelids, Arthropods.

Vertebrates having –

Two-chambered hearts: Chrondrichytes and osteichytes

Three- chambered heart: Amphibia and Reptile

Four-chambered heart: Aves and mammalian

In two-chambered heart, there is one atria and one ventricle present which are not separated due to which oxygenated and deoxygenated blood mixes.

Three-chambered heart is developed due to the division of auricle into right and left halves.

In four chambered heart, both the auricle and ventricle are divided into two halves and thus no mixing of oxygenated and deoxygenated blood.

A = Malpighian tubules

Explanation: In Arthropods, the Malpighian tubules remove excretory products from haemolymph.

B = Open

Explanation: Arthropods have what is referred to as an open circulatory system, where blood fills the body cavity of the animal.

C = Annelida

Explanation: Members of phylum Annelida has nephrida as excretory organs, closed circulatory system and they respire through skin/parapodia.

D = Mollusca

Explanation: In mollusca, have metanephridia and circulatory system is open.

E = Feather-like gills

Explanation: Molluscs have feather-like gills for respiration.

F = Amphibians have kidneys as their excretory organs.

a. Amphibia – Dual habitat

Explanation: The word amphibia itself means two lives. The amphibians live on land as well as in water.

b. Mammals – Mammary glands

Explanation: The mammals have mammary glands to release milk to nourish their young ones.

c. Chondrichthyes – Cartilagenous notochord

Explanation: Chondrichthyes have cartilaginous notochord at a young stage but it is replaced by cartilage later.

d. Osteichthyes – Air bladder

Explanation: Osteichthyes have a sac which contains air. This sac is called Air bladder.

e. Cyclostomata – Sucking and circular mouth without jaws

Explanation: Cyclostomes have sucking and circular mouth without jaws which is surrounded by tentacles and the tongue bears teeth

f. Aves – Pneumatic bones

Explanation: Aves have bones which are hollow and filled with air. Such bones are called pneumatic bones. This makes them light weight.

Endoparasites have extreme specialisations which makes their life cylces more complex.

To survive inside the host body, the evolve the following adaptations –

• High reproductive capacity

• Presence of adhesive organs or suckers to cling on to the host.

• Loss of digestive system.

• Loss of unnecessary sense organs.

a. Pila – Presence of shell

b. Cockroach – Jointed appendages

c. Asterias – Water vascular system

d. Torpedo – Electric organ

e. Parrot – Perching

f. Dog fish – Placoid scales

a. Open and closed circulatory system

b. Oviparity and viviparity

c. Direct and indirect development

d. Aceolomate and pseudocoelomate

e. Notochord and nerve cord

f. Polyp and medusa

a. Chondrichthyes and ostichthyes

Chodrichthyes :

• Their habitat is mainly marine and their body is streamlined. They have cartilaginous endoskeleton.

• Mouth is ventrally (near the front of the body) located.

• Notochord is persistent throughout the life.

• The air bladder is absent due to which they have to swim constantly to prevent sinking.

• They have tough skin, containing placoid scales. The teeth are modified placoid scales directed backwards.

• Heart is 2-chambered and they are cold blooded.

• Gill slits are separated and without operculum (cover for gills)

• Examples – Scoliodon, Pristis , Trygon

Ostichthyes

• The habitat is both marine as well as freshwater and they have a streamlined body. The endoskeleton is bony.

• Mouth is mostly terminal.

• Air bladder is present which gives buoyancy.

• There are 4 pairs of gills with operculum present.

• They are cold blooded.

• Heart has 2 chambers (1 auricle and 1 ventricle).

• Skin is covered with cycloid/ctenoid scales.

• Examples – Marinee : Hippocampus (Sea horse), Freshwater : Labeo (Rohu), Aquarium : Betta (Fighting fish)

b) Urochordata and cephalochordata

• Phylum chordata is divided into three categories – urochordata, cephalochordata and vertebrate.

• Urchordata and cephalochordate are often referred to as protochordates.

• They are exclusively marine.

• In urochordates, the notochord is present only in larval tail but in cephalochordates, notochord extends from head to tail region and is persistent throughout the life.

• Examples – Urochordates: Ascidia , Salpa , Cephalochordates : Branchiostoma.

a) Aves and Mammals

• Both aves and mammals are warm-blooded animals.

• Both have 4-chambered heart.

b) A frog and crocodile

• Both are cold-blooded animals

• Both are oviparous animals

c) Turtle and pila

• Both are cold –blooded animals

• Both are oviparous animals.

a. A limbless animal – Icthyophis

b. A cold blooded animal - Trygon

c. A warm blooded animal – Macaca (monkey)

d. An animal possessing dry and cornified skin – Naja (Cobra)

e. An animal having canal system and spicules – Euspongia

f. An animal with cnidoblasts - Hydra

a. A viviparous animal – Panthera leo

b. A fish possessing a poison sting – Trygon

c. A fish possessing an electric organ – Torpedo

d. An organ, which regulates buoyancy – Air bladder

e. Animal, which exhibits alternation of generation – Obelia

f. Oviparous animal with mammary gland – Echidna

a. Balanoglossus – Proboscis gland

b. Leech – Nephridia

c. Locust – Malpighian tubule

d. Liver fluke – Flame cells

e. Sea urchin – Absent

f. Pila – Metanephrida

a) The early embryo acquires fundamental cell layers by a process called gastrulation. These layers are called germinal layers or germ layers.

b) The outer germinal layer is called ectoderm (formation of ganglia, Central nervous system, glands, etc.), the middle one is called endoderm (involved in the formation of skeleton, skeletal muscles, the dermis ok the skin, etc.) and the innermost is endoderm (associated with the formation of stomach, colon, livers, etc.)

c) Coelomates are the organisms possessing coeloms. Coelom is the body cavity lined by the mesoderm. Examples of coelomates are phylum annelida, mollusca , arthropoda, etc

d) The organisms with absent body cavities are called aceolomates. E.g. Platyhelminthes

e) In some organisms, body cavity is not lined by mesoderm, instead mesoderm is present in the form of scattered pouches in between ectoderm and endoderm, Such body cavity is called pseudocoelom and animals possessing pseudocoelom are refered to as pseudocoelomates e.g.,Ascaris.

Amphibia–

a) They can live on land as well as in water.

b) They have thin and moist skin (without scales)

c) Their eyes have eye lids.

d) Most of them have two pairs of limbs.

e) A tympanum is representing the ears.

f) Examples – Rana(frog), Salamander, Naja (cobra)

Reptiles–

a) They mostly live on land.

b) Their body is covered with dry and cornified skin and scales.

c) Tympanum represents ear.

d) Have two pairs of limbs. Their mode of locomotion is mainly creeping and crawling.

e) They are oviparous, fertilization is internal and development is direct or indirect.

f) Examples – Crocodile, turtle, tortoise

Mammals are the most adapted among the vertebrates because –

a) They are found in a variety of habitats like deserts, plains, mountains, polar ice caps, forests, etc.

b) Different types of teeth in the jaw.

c) Sexes are separate and fertilization is internal.

d) Have 2 pairs of limbs which are used for walking, burrowing, climbing, running, flying.

e) Mammals have mammary glands to produce milk to nourish their young ones.

f) Mammals are warm-blooded which helps them maintain their body temperature in different weather conditions.

g) The skin of mammals has hair which acts as insulation against cold.

h) They have sweat and oil glands which also help in temperature control.

i) A 4-chambered heart is present in mammals.

j) The brains are more developed.

k) Examples of Mammals : Humans, Whales, Dogs, Camels, etc