Railway Science (Biology – Animal Kingdom)

Areolar connective tissue is found between the skin and muscles, around blood vessels and nerves and in the bone marrow.

Fish have a two-chambered heart, consisting of one atrium and one ventricle. This circulatory system is known as single circulation, meaning blood passes through the heart only once to complete a circuit through the body.

Arthropoda: The largest phylum in the animal kingdom, which includes such familiar forms as lobsters, crabs, spiders, mites, insects, centipedes, and millipedes. Mollusca is the second largest animal phylum. It is terrestrial or aquatic having an organ system level of organisation.
They are bilaterally symmetrical, triploblastic and coelomate animals. Annelids (ringed worms or segmented worms) - A large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. Echinodermata are round or elongated and have a star-like appearance. Examples: Asterias, Ophiura.

Heart Chambers in Vertebrates: Fish: 2 chambers (1 atrium, 1 ventricle). Amphibians and reptiles (except crocodiles): 3 chambers (2 atria, 1 ventricle). Crocodiles, Birds and mammals: 4 chambers (2 atria, 2 ventricles).

Monera : They contain 70s ribosomes. The DNA is naked and is not bound by a nuclear membrane. Its cell wall is rigid and made up of peptidoglycan. Fungi are eukaryotic organisms and have a nucleus with a membrane as well as other membrane-bound organelles. Plantae: This kingdom encompasses all multicellular eukaryotic plants, from mosses to trees.

The most distinctive feature of echinoderms is the presence of a water vascular system which helps in locomotion and transport of food and respiration. An excretory system is absent. Examples: Asterias (Star fish), Echinus (Sea urchin), Antedon (Sea lily), and Cucumaria (Sea cucumber).

Members of phylum Porifera are commonly known as sponges. They are generally marine and mostly asymmetrical animals. These are primitive multicellular animals and have cellular level of organisation. Examples of Porifera: Sycon (Scypha), Spongilla (Freshwater sponge) and Euspongia (Bath sponge).

They belong to phylum Platyhelminthes found in freshwater bodies and exhibit remarkable regenerative abilities. This phylum comprises flatworms, which are characterized by their flattened, ribbon-like bodies. Ascaris belongs to the phylum Nematoda, commonly known as roundworms.

Echinodermata : This phylum includes animals with radial symmetry, a spiny endoskeleton made of calcium carbonate, and a water vascular system for feeding. Examples - starfish, sea urchins, sand dollars.
Other Group and Example : Annelida - Earthworms, leeches, and polychaetes, Porifera - Sponges, and Nematoda - Pinworms and hookworms.

Reptiles are the class of animals that have dry, scaly, gland-less skin. They are creeping and burrowing terrestrial animals with scales on their body and are cold-blooded animals. Examples of reptiles include snakes, lizards, turtles, and crocodiles.