Classification of Animals Test - 7

The phylum Arthropoda includes animals with jointed legs and appendages. This is the largest phylum of the animal kingdom containing about 9 lacs species, which is approximately 85 percent of the total number of species of animals. Thus option A is the correct answer.

The common starfish is to be found on rocky and gravelly substrates where it feeds on molluscs and other benthic invertebrates (Benthos is the community of organisms that live on, in, or near the seabed, river, lake, or stream bottom, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths)

Thus, the correct answer is option C.

The phylum Arthropoda includes animals with an exoskeleton.

They are mostly unisexual and exhibit sexual dimorphism but some are hermaphrodites.

Arthropods belonging to the class Insecta show metamorphosis in their life cycle.

In terrestrial arthropods, fertilization is internal but aquatic arthropods show internal as well as external fertilization.

Thus the correct answer is option D.

They all belong to the phylum Arthropoda( Joint appendages).

Appendages - Some or all the segments bear appendages. The appendages are jointed. It is variously modified for feeding, walking, jumping, swimming, clinging, sensory reception, copulation and defence.

Body wall- The body wall consists of a thick, chitinous cuticle and a single layered epidermis. The hard cuticle restricts growth and is periodically changed during growth. The process is called moulting or ecdysis.

So, the correct answer is 'Joint appendages and chitinous exoskeleton'.

A) Echinoderms are dioecious (have separate sexes on separate individuals)

B) Echinoderms are not monoecious (having both sexes on the same individual).

C) Echinoderms are not monoecious. 

D) Echinoderms are not monoecious. 

So the answer is 'Dioecious'.

Pila is a genus of freshwater snail of family Ampullariidae. It belongs to phylum Mollusca. It has unsegmented body. Asterias is a genus of the Asteriidae family. It belongs to phylum Echinodermata. It has hydraulic system called as water vascular system for locomotion, feeding and respiration. Sycon is a genus of calcareous sponges belonging to the family Sycettidae. It belongs to phylum Porifera. Porifera means pore bearing. It has canal system with is used for locomotion, feeding and reproduction. Periplaneta is a genus of cockroaches. It belongs to phylum Arthropoda. It has joined appendages and chitinous exoskeleton. 

Thus, the correct answer is option A.

Animals with three pairs of legs belong to phylum Arthropoda. An arthropod is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages. They are characterized by the cuticle made of chitin, often mineralized with calcium carbonate.

The mollusks compose the large phylum of invertebrate. They include snails, slugs and other gastropods; clams and other bivalves; squids and other Cephalopoda such as squid, cuttlefish, and octopuses because they possess key characteristics of Mollusca i.e., soft unsegmented body covered with hard calcareous shell.

Thus, the correct answer is option A.

Terrestrial molluscs are also called as land molluscs. It includes all molluscs that lives on land. It belongs to  class Gastropoda. It includes land snails and land slugs. Example of land snail includes Helix pomatia. Example of land slug includes Limax cinereoniger.

Thus, the correct answer is option D.

Starfish is a triploblastic, radially symmetrical animal having a spiny body surface. These characteristics belong to Echinodermata. About 1,500 species of starfish occur on the seabed in all the world's oceans, from the tropics to frigid polar waters. They are found from the intertidal zone down to abyssal depths, 6,000 m (20,000 ft) below the surface. Thus, option B is correct.

Echinodermata includes marine animals which have spiny body surface and calcareous exoskeleton. They are triploblastic coelomates. They are radially symmetrical in adult stage but shows bilateral symmetry in the larval stage.

Thus, the correct answer is option C.

Molluscs are mostly aquatic. Their soft bodies are enclosed in a hard shell made of calcium carbonate (CaCO3), which functions as an exoskeleton. This shell is secreted by the mantle, which encloses the internal organs such as heart, kidney, gonads etc. The mantle creates a small empty space called a mantle cavity, which is modified for different functions in different groups of molluscs.

Molluscs are sea animals which possess certain minerals required for the human diet. The mollusc shell is a calcareous exoskeleton, rich in zinc and iodine. It encloses, supports and protects the soft body parts of the molluscs. This makes the molluscan shells be used for ointments preparation and several other medicines where zinc and iodine are inevitable. Thus, the correct answer is option D.

Mollusca are the phylum of the soft unsegmented animal whose body is covered with the hard calcareous shell. Molluscs like clams, mussels are used as food sources whereas some are used as a luxury good because they produce pearls inside their shells. Thus, the correct answer is option C.

Snail, octopus, pila are aquatic animals have a unsegmented body covered with the calcereous shell. They are triploblastic and shows bilateral symmetry except Pila which is asymmetric. Thus, they belong to the phylum Mollusca.