Category: Biology Second Paper

Liver worm- Fasciola hepatica
Tape worm – Taenia solium
Dog tapeworm – Echinococcus granulosus
Free-living flatworm – Dugesia tigrina
Hammer head worm- Bipalium kewense
Human bloodworm – Schistosoma mansoni
Frog worm- Polystoma integrimum
Gyrodactylus- Gyrodactylus corti
Dactylogyrus alatus
Convoluta- Convoluta convoluta
Microstomum- Microstomum lineare
Thysanozoon – Thysanozoon brocchii
Sheep worm- Dicrocoelium dendriticum

The cyst is a part of the excretory organ. Cells are bulbous with holes. It is attached to the tube of mesoderm. It has cilia in clusters. The cilia vibrate violently inside the tube, creating a current of water. As a result, the waste material is released through the excretory hole. Thus it helps in digestion.

The order Platyhelminthes is divided into 4 classes.
1. Turbellaria: Their bodies are flat like leaves. Cuticle is absent on the body. The epidermis is ciliated and rhabdite in nature. Suction is missing. Larval stage absent. They are known as Edewam. Such as Planaria (Dugesia tigrina).
2. Trematoda: They are cylindrical or flat like leaves. Cilia are absent on the body. The mouth has suckers or hooks. Larval stage present. They are known as Fluke. For example- liver worm (Fasciola hepatica).
3. Monogenia: These are small parasites. Their heads contain nerve cells and sensory organs. Alimentary canal is simple in nature. They are known as flatworms. Such as Planaria (Dugesia tigrina).
4. Cestoda: Their bodies are long and flattened like ribbons. Composed of 800-900 proglottid segments. Each segment has one or two sets of male or female reproductive organs. The mouth has suckers and curved hooks. Mouth opening and esophagus absent. They are known as tapeworms. For example, tapeworm (Taenia solium).

1. They are triploblastic animals. That is, the body has cell layers called ectoderm, endoderm and mesoderm.
2. The body is bilaterally symmetrical and flattened like a leaf or ribbon.
3. They are Asilomates. Between different organs are parenchyma or collenchyma cells.
4. Body skin is soft, without cilia or cuticles.
5. The mouth has suckers or hooks or proglottids.
6. The excretory system is made up of flame cells.
7. The nervous system is ladder-like and consists of ganglia and digitorum plexus.
8. Their epidermis is composed of syncytes.
9. Circulatory system and respiratory system are absent.
10. Alimentary system is incomplete, branched and consists of mouth, pharynx and intestine. There is no anus.
11. They self-destruct. The life cycle consists of larvae such as radia, cercoria, sporocysts, cysticercus etc.
[Key words to remember characteristics: triploblastic, flattened, parenchyma, autophagic, sucker, hook, flame cell, syncytial]

The word Platyhelminthes is formed from the Greek words platy meaning flat and helminth meaning worm. Animals of this group are known as flatworms or tapeworms. The number of species in this category is about 29,487. The group Platyhelminthes was named by the scientist Gagenbaur (Gagenbaur, 1859). Some flatworms of the genus cause schistosomiasis or snail fever in humans.

The word Cnidaria is formed by combining the Greek word knide meaning thorn and the Latin word area. Nidarians are called flower of the sea. The former name of the order Nidaria is Cilenterata. The marine animal Chironex fleckeri is the world’s most poisonous jellyfish (it can kill 67 people). Animals of this phase form colonies under the sea like a tropical rain forest. They form reefs or reefs. The number of species in this category is about 10,203. Cnidaria was named by scientist Leuckart (1847).

Characteristics of Cnidaria
1. They are diploblastic animals. That is, their cells have two cell layers called ectoderm and endoderm.
2. Between the ectoderm and endoderm is an acellular layer called mesoglia.
3. Their body shape is filamentous, tubular and umbellate.
4. The body consists of nidoblast cells, which bear nematocysts.
5. There is a body cavity called gastrovascular or cilantern. The cilianteron is called the alimentary canal. It acts as the mouth and anus and participates in digestion and transport.
6. Cellular and organelle division of labor is seen.
7. The life cycle includes genetics, metagenesis and polymorphism.
8. In the life cycle there are stationary polyp dasa and active medusa dasa.
9. Body does not have organ system, respiratory system and circulatory system. The nervous system is underdeveloped.
10. They are multicellular, asymmetrical and headless.
11. Food material is digested extracellularly and intracellularly.
12. Respiration occurs through ciliated planula larvae.
13. Twenty species of Nidaria are freshwater. The remaining Nidaria are marine.
Characteristics Key words to remember: diploblastic, mesoglia, nidoblast, coelenteron, division of labor, metagenesis, polymorphism, polyp, medusa]

Classification of Cnidaria
The order Cnidaria is divided into 4 classes.
1. Hydrozoa: They live in water. Polyp or medusa stages are seen in the life cycle. Mesoglia are cellless. Genitalia arise from ectoderm. Like- Hydra viridis, Obelia geniculata.
2. Scyphozoa: These are cup or bell or umbrella shaped animals. Medusa Dasha is the main one in the life cycle. Genitalia arise from endoderm. Mesoglia are large and composed of cells and fibers. For example, Aurelia aurita
3. Cubozoa: They are storm-like creatures. Their Medusa Dasa is the main one. For example, Metridium
4. Anthozoa: They are flower-shaped organisms. A polyp stage is present in the life cycle. Mesoglia are composed of fibrous connective tissue. Genitalia arise from endoderm. For example, Metridium senil, Gorgoni verrucosa.

Some animals of Cnidaria
Hydra – Hydra vulgaris
Chlorohydra – Chlorohydra viridissima
Jellyfish – Aurelia aurita
Portuguese Man of War – Physalia physalis
Adamsia – Adamsia palliata
Obelia- Obelia geniculata
Sea fan – Gorgonia ventilina
Sea feather – Pennatula aculeata
Sea saffron – Metridium senile
Carydea- Carybdea alata
Cyanea – Cyanea capillata
Chironex – Chironex fleckeri
Brain Coral – Meandrina meandrites
Gorgonia- Gorgonia verrucosa
Red Coral – Corallium rubrum
Kamangola jelly – Stomolophus meleagris

Jelly fish
Jellyfish are marine animals belonging to the order Nidaria. It consists of a hanging part called manubrium. There are four oral arms with shafts. Numerous hollow cores exist. For example – Aurelia aurita.

Jellyfish are marine animals belonging to the order Nidaria. It consists of a hanging part called manubrium. There are four oral arms with shafts. Numerous hollow cores exist. For example – Aurelia aurita.

Hydra – Hydra vulgaris
Chlorohydra – Chlorohydra viridissima
Jellyfish – Aurelia aurita
Portuguese Man of War – Physalia physalis
Adamsia – Adamsia palliata
Obelia- Obelia geniculata
Sea fan – Gorgonia ventilina
Sea feather – Pennatula aculeata
Sea saffron – Metridium senile
Carydea- Carybdea alata
Cyanea – Cyanea capillata
Chironex – Chironex fleckeri
Brain Coral – Meandrina meandrites
Gorgonia- Gorgonia verrucosa
Red Coral – Corallium rubrum
Kamangola jelly – Stomolophus meleagris

The order Cnidaria is divided into 4 classes.
1. Hydrozoa: They live in water. Polyp or medusa stages are seen in the life cycle. Mesoglia are cellless. Genitalia arise from ectoderm. Like- Hydra viridis, Obelia geniculata.
2. Scyphozoa: These are cup or bell or umbrella shaped animals. Medusa Dasha is the main one in the life cycle. Genitalia arise from endoderm. Mesoglia are large and composed of cells and fibers. For example, Aurelia aurita
3. Cubozoa: They are storm-like creatures. Their Medusa Dasa is the main one. For example, Metridium
4. Anthozoa: They are flower-shaped organisms. A polyp stage is present in the life cycle. Mesoglia are composed of fibrous connective tissue. Genitalia arise from endoderm. For example, Metridium senil, Gorgoni verrucosa.

1. They are diploblastic animals. That is, their cells have two cell layers called ectoderm and endoderm.
2. Between the ectoderm and endoderm is an acellular layer called mesoglia.
3. Their body shape is filamentous, tubular and umbellate.
4. The body consists of nidoblast cells, which bear nematocysts.
5. There is a body cavity called gastrovascular or cilantern. The cilianteron is called the alimentary canal. It acts as the mouth and anus and participates in digestion and transport.
6. Cellular and organelle division of labor is seen.
7. The life cycle includes genetics, metagenesis and polymorphism.
8. In the life cycle there are stationary polyp dasa and active medusa dasa.
9. Body does not have organ system, respiratory system and circulatory system. The nervous system is underdeveloped.
10. They are multicellular, asymmetrical and headless.
11. Food material is digested extracellularly and intracellularly.
12. Respiration occurs through ciliated planula larvae.
13. Twenty species of Nidaria are freshwater. The remaining Nidaria are marine.
Characteristics Key words to remember: diploblastic, mesoglia, nidoblast, coelenteron, division of labor, metagenesis, polymorphism, polyp, medusa]