Samacheer Class 11 Bio Zoology - Kingdom Animalia

Cyclostomata
Chondrichthyes
1. Some are ectoparasites on some fishes.
They are free living.
2. Body is slender and eel-like
Skin is tough and covered with placoid scales
3. 6 to 15 pairs of gillslits for respiration.
Respiration is by lamelliform gills.
4. Mouth is circular without jaws and suctorial.
There are lower and upper jaws.
5. Migrate to freshwater for spawning
There is no migration during breeding.
6. After spawning they die
They don’t die after spawning
7. Oviparous
Oviparous, viviparous and Ova viviparous

• These fishes have a bony endoskeleton.
• The skin is covered by ganoid, cycloid or ctenoid scales.
• Gills are covered by an operculum.
• They are ammonotelic.
• They have mesonephric kidneys.
• External fertilization is seen.

• The characteristics that contribute to the success of reptiles on land are as follows:
• The presence of dry and cornified skin with epidermal scales or scutes prevents the loss of water.
• The presence of metanephric kidney.
• They are uricotelic (they excrete uric acid to prevent the loss of water).

No. The number of eggs or young ones produced by an oviparous and viviparous female cannot be equal. When the oviparous animals lay eggs in the external environment or in the medium, the chance of survival and successful development into the adults are not certain. But in the case of viviparous animals, young ones are nurtured by the adult animals. Hence, oviparous animals lay more eggs if they are fertilized in the medium or in water.
Part-II
11th Bio Zoology Guide Kingdom Animalia Additional Important Questions and Answers
I. Choose The Best Options

All vertebrates possess notochord during the embryonic stay. li is repLaced by vertebra) column. All vertebrates possess pained appendages such as fins or lunits. Skin is covered by a protective skeleton comprising of scales. feathers hairs, claws, nails, etc. Respiration is aerobic through gills, skin. buccopharyngeal cavity’ and lungs. All vertebrates have a muscular heart with two, three, or four chambers and kidneys for excretion and osmoregulation.

Open Circulation
Closed Circulation
1. There are no blood vessels
Presence of blood vessels.
2. Blood remains filled in the tissue spaces.
Blood is circulated through blood vessels
3. (Eg.) Arthropods, Mollusca, Echinodermata
(Eg.) Earthworm, Cephalochordates, Chordates

Schizocoelomate
Enterocoelomate
1. Body cavity is formed by splitting of mesoderm.
The body cavity is formed from the mesodermal pouches or archenterons.
2. (Eg.) Annelids, Arthropods
(Eg.) Echinodermata Chordates

• Notochord, cephalization, dorsal nerve cord, and radial symmetry.
• Notochord, cephalization, and dorsal nerve cord are the characteristic features of chordates. The radial symmetry is not a characteristic feature of chordate. It is the feature of cnidarian and adult echinoderms. Hence it does not belong to the group.

Invertebrates:
* The major group of animals which do not have notochord or vertebral column are Invertebrates.
* These are lower animals.
Chordates:
* The major group of animals which have notochord or vertebral column are chordates.
* These are higher animals.

The inner layer of sponges has a special type of cells called choanocytes. These flagellated collar cells create and maintain water flow through the sponge. It helps in respiration and digestion.

Incomplete Digestive System
Complete Digestive System
1. There is a single opening in the digestive system which serves as both mouth and anus.
(Eg.) Platyhelminthes
1. There are separate openings for the mouth and anus. (Eg.) Chordates

The animals which lack a definite body plan and any plane passing through the center of the body does not divide them into two equal halves are known as asymmetrical animals, e.g. Sponges.

The bilaterally symmetrical animals can seek food, locate mates, escape from predators and move more efficiently. These animals have dorsal-ventral sides and anterior, posterior ends, right and left sides. They exhibit cephalization with sense organs and brain at the anterior end of the animal.

The animals which have a body cavity that is not fully lined by the mesodermal epithelium are called pseudocoelomates. The pseudocoel is filled with pseudocoelomic fluid. It acts as a hydrostatic skeleton and allows free movement of visceral organs and circulation of nutrients e.g. Roundworms.

Schizocoelomates:
In schizocoelometes, the body cavity is formed by splitting mesoderm, e.g. Annelids, arthropods, and mollusks.
Enterocoelomates:
In enterocoelomates, the body cavity is formed from the mesodermal pouches of the archenteron. e.g. Echinoderms, hemichordates and chordates.
(3 marks)
III. Short Questions

Animals exhibit different patterns of organisation:
The cellular level of organisation:
* Cells are loosely arranged without the formation of tissues.
* There is a division of labour among the cells, e.g., sponges.
Tissue level of organisation:
* Cells which perform a similar function are grouped into tissues.
* The tissues perform a common function, e.g., cnidarians.
Organ level of organisation:
Different kinds of tissues aggregate to form an organ to perform a specific function e.g., flatworms and other hyper phyla.
Organ system level of organisation:
* The tissues are organized to form organs and organ systems.
* All the organ systems function in a coordinated manner.

The cavity between the body wall and the gut wall is called coelom. If the animals do not have coelom, they are called acoelomates. e.g., flatworms. In some animals, the body cavity is not fully lined by the mesodermal epithelium. The mesoderm is formed as scattered pouches between the ectoderm and endoderm. Such a body cavity is called a pseudocoel. The animals which have pseudocoel e.g. roundworms.
If the coelom develops within the mesoderm and is lined by mesodermal epithelium it is called eucoelom. The animals which have true coelom are called eucoelomates. If the body cavity is formed by splitting of mesoderm, the animals are called schizocoelomates e.g., Annelids, arthropods and mollusks. If the body cavity is formed from the mesodermal ‘ pouches of archenteron, the animals are called enterocoelomate animals, e.g., echinoderms, hemichordates and chordates.
(5 Marks)
IV. Essay Questions

Animals exhibit different patterns of organisation:
The cellular level of organisation:
* Cells are loosely arranged without the formation of tissues.
* There is a division of labour among the cells, e.g., sponges.
Tissue level of organisation:
* Cells which perform a similar function are grouped into tissues.
* The tissues perform a common function, e.g., cnidarians.
Organ level of organisation:
Different kinds of tissues aggregate to form an organ to perform a specific function e.g., flatworms and other hyper phyla.
Organ system level of organisation:
* The tissues are organised to form organs and organ systems.
* All the organ system function in a coordinated manner.

• The animals are marine, diploblastic and radially symmetrical.
• They have eight external rows of ciliated comb plates which help in locomotion.
• Bioluminescence is seen.
• They lack nematocysts but have lasso cells which help in food capture.
• Digestion is by both extracellular and intracellular.
• Sexual reproduction is seen.
• Fertilization is external and development is indirect.
• Cydippid larva is seen, e.g., Pleurobrachia.

Platyhelminthes
Aschelminthes
1. The body is flattened one
They are round in shape.
2. They are bilateral and triploblastic animal.
They are bilateral and triploblastic animal.
3. Acoelomate
Pseudo coelom is present.
4. They have pseudo segmentation
The body is unsegmented
5. Excretion is through flame cells.
Excretion is through rennet glands.
6. Sexes are not separate.
They are monoecious.
Sexes are separate and exhibit sexual dimorphism.
7. Some show regeneration capacity.
No regeneration capacity.
8. Larva is present.
No larva
9. (Eg.) Tape worm, Planeria
(Eg.) Ascaris

• Molluscs are terrestrial or aquatic with organ system level of organisation.
• They are triploblastic, bilaterally symmetrical, coelomate animals.
• Body is divided into head, foot and visceral hump.
• The digestive system is complete.
• Nephridia are the excretory organs.
• Open type of circulatory system is seen.
• Blood contains a copper-containing respiratory pigment called hemocyanin.
• They are oviparous.
• Development is indirect with a veliger larva, e.g., Pila and Octopus.

• The Hemichordates have both invertebrate and vertebrate characters.
• They are worm-like, tuberculous animals.
• They are bilaterally symmetrical, triploblastic coelomate animals with organ system level of organisation.
• The body is divided into proboscis, collar, and trunk.
• They are ciliary feeders.
• The circulatory system is simple and open.
• Excretion is by a single proboscis gland or glomerulus situated in the proboscis.
• Sexes are separate.
• Fertilization is external.
• Development is indirect with tomaria larva, e.g., Balanoglossus.

• They are marine found in shallow waters.
• They lead a burrowing mode of life.
• They are fish-like with notochord, nerve cord and pharyngeal gill slits throughout their life.
• Closed type of circulatory system is seen without heart.
• Excretion is by protonephridia.
• Sexes are separate.
• Fertilization is external.
• Development is indirect with a larva e.g. Amphioxus.

• The body is covered by hairs.
• They are found in a variety of habitats.
• The presence of the mammary gland is the most unique feature of mammals.
• They have two pairs of limbs.
• The skin consists of sweat glands and sebaceous glands.
• Exo skeleton includes horns spines, scales claws, etc.
• Teeth are thecodont heterodont and diphyodont.
• The heart is four-chambered and posses a left systematic arch.
• Mammals have a large brain when compared to other animals.
• Their kidneys are metanephric and are ureotelic.
• All are homeothermic.

* Presence of notochord below the nerve chord and above the alimentary canal.
* The presence of the nerve cord lies above the notochord and below the dorsal body wall.
* Presence of pharyngeal gill slits in all chordates at some stage of their life cycle.
Features saw in the matured adult animals
Larva
Adult
Notochord
It may be partially or completely replaced by a backbone.
Nerve cord
They enlarged to form the brain and spinal cord.

Chordates
Non-chordates
1. Notochord is present
Absence of notochord.
2. Dorsal hollow and single nerve cord
Double ventral solid nerve cord.
3. Pharynx perforated by gill slits.
Gill slits absent.
4. Heart is ventrally placed.
Heart indoors or laterally placed or absent.
5. A post-anal tail is present
Post anal tail is absent
6. Alimentary canal placed ventral to the nerve cord
The alimentary canal is placed dorsal to the nerve cord.