Liver fluke - Belongs to group platyhelminthes. Platyhelminthes is a group of triploblastic animals.

The number of chambers in the heart depends on the complexity of the body organization. For example, mammals are more complex and therefore, they possess maximum number of chambers in the heart  (four-chambered heart) and fishes have less complex body organization than mammals, so they possess less number of chambers in the heart than found in case of mammals. Piscean - These are fishes. They are exclusively water animals. Their skin is covered with scales/plates. They obtain oxygen dissolved in water by using gills. They are cold-blooded and have two-chambered heart.  

 Whale, the largest mammal, lives in water. Mammals are warm-blooded animals with four-chambered hearts. They have mammary glands for the production of milk to nourish their young ones. Their skin has hair as well as sweat and oil glands. 

Mollusca: In the animals of this group, there is bilateral symmetry (the left and the right halves of the body are same in design) with little segmentation. The coelom (body cavity) is reduced. They have an open circulatory system (blood does not flow in blood capillaries) and bear kidney-like organs for excretion of waste material. There is a foot, which is used for moving, e.g. unio, chiton, pila, octopus, etc. 

Amphibians - ‘Amphi' means 'both' and 'bios' means life. Animals that spend some time on land must breed (mate and produce young ones) and develop into an adult under water. Amphibians possess both lungs and gills for respiration. For example, frogs, toads and salamanders. Therefore, they can live both on land and in water. 

Notochord (chord – string) is a long, flexible rod-like structure that provides support to the body. Animals that possess notochord are called chordates and animals without notochord are called non-chordates, e.g. platyhelminthes, porifera, coelenterata, nematoda, annelida, arthropoda, mollusca, echinodermata, etc. are all non-chordates. 

Reason: Coelom is a true internal body cavity between body wall and digestive tract of many animals in which well-developed organs can be accommodated. 

Spongilla belongs to the group porifera. They are commonly known as sponges. The word ‘porifera’ means organisms with holes. These are non-motile animals attached to some solid support under water. They have holes or ‘pores’ all over the body. These lead to a canal system, which helps in circulating water throughout the body to bring in food and oxygen. The members of this phylum lack mouth and anus. 

Spores - Thallophytes, bryophytes & pteridophytes have naked embryos that are called spores. The reproductive organs in these three groups are invisible and therefore they are called 'cryptogams' or “those with hidden reproductive organs”.

Presence of naked embryo - Thallophytes, bryophytes & pteridophytes have naked embryos that are called spores. 

Angiosperms - bear seeds that develop inside the organ, which is modified to become a fruit Reason: Phanerogams - Plants with well differentiated reproductive tissues which ultimately make seeds. 

Phanerogams (Gymnosperm and Angiosperm) are the plants that reproduce by means of seeds and not by spores. They are the plants that produce seeds. 

Reason: In angiosperms, plant embryos in seeds have structures called cotyledons. Cotyledons are called 'seed leaves' because when they emerge during seed germination they become green. Thus, cotyledon represents pre-design plant in the seed. The angiosperms are divided into two groups based on the number of cotyledons present in the seed. (1) Monocotyledonous or monocots - Plants with seeds having single cotyledon, e.g. Paphiopedilum (2) Dicotyledonous or dicots - Plants with seeds having two cotyledons, e.g. Ipomoea. 

Aves (birds) are warm blooded animals and have four chambered heart, e.g. ostrich, duck, etc. Mammals also have four chambered heart. Two-chambered heart- is found in pisces (fishes). Three-chambered heart – is found in amphibia (e.g. frogs, toads) and all reptiles (lizards, snakes) except crocodiles as they have four-chambered heart.

Oviparous: are the animals that reproduce by means of eggs that develop and hatch outside the mother's body. Examples are birds, fishes, insects and reptiles. Therefore, fish belongs to oviparous category. 

Coelom is an internal body cavity between body wall and digestive tract of many animals in which well-developed organs are present.

Dog fish (Generic name - Scolidon) also known as small shark belongs to class- Pisces (fishes). They are exclusively water living. Their skin is covered with scales or plates. They obtain oxygen dissolved in water with the help of gills. The body is streamlined and a muscular long tail is used for movement in water. They are cold-blooded and have two-chambered heart. They lay eggs (Oviparous). 

Elephantiasis is a disease of lymphatic system (a network of vessels that transport fluid, fat, proteins and white blood cells to the bloodstream as lymph and remove micro organisms from tissues). A large enlargement of the infected area characterizes this disease. The hardened skin of the infected area resembles the hide (skin) of an elephant. That is the reason why this disease is known as elephantiasis. The disease is caused by the blockage of the lymphatic system by thread-like filarial worms, usually Wuchereria bancrofti (a nematode). The parts of the body most frequently affected are the limbs. The disease is treated with the antifilarial drug or with surgery. 

Aves (Birds) - These are warm-blooded animals and each has four-chambered heart.

Coelom is a true internal body cavity between body wall and gut of many animals in which well developed organs can be accommodated. Based on the coelom, animals are divided into following types: Acoelomate: An organism with no cavity or coelom between its digestive tract and outer wall. For example, flatworms and jelly fish. Pseudocoelomate: (Pseudo - false, coelom - body cavity). Nematode is an example of pseudocoelomate. The nematode body is simple and cylindrical rather than flattened. There are tissues, but no real organs, although a type of body cavity is present, which is known as pseudocoelom. For example, Ascaris (roundworm), Wuchereria. Coelomate: Animals with true body cavity. For example, annelida, mollusca, arthropoda, chordata, echinodermata.