Diversity in Living Organisms

Male frogs can be distinguished by the presence of sound producing vocal sacs and also a copulatory pad on the first digit of the forelimbs, which are absent in female frogs.

The frog never drinks water but absorbs it through the skin.

Bioluminescence (the property of a living organism to emit light) is well-marked in ctenophores.

Saccoglossus belongs to hemichordata. Hemichordata consists of a small group of worm-like marine animals with organ-system level of organisation.

Sponges are mostly asymmetrical, i.e. any plane that passes through the centre does not divide them into equal halves.

Ctenoplana belongs to phylum Ctenophora. It body bears eight external rows of ciliated comb plates, which help in locomotion.

In coelenterates, the arrangement of cells is more complex. Here, the cells performing the same function are arranged into tissues, hence is called tissue level of organization.

Those animals in which the developing embryo has a third germinal layer, mesoderm, in between the ectoderm and endoderm, are called triploblastic animals e.g. platyhelminthes to chordates.

Specialised cells called flame cells that help in osmoregulation and excretion are present in flatworms (platyhelminthes).

Arthropods are bilaterally symmetrical, triploblastic, segmented and coelomate animals.

Salpa belongs to Urochordata. In Urochordata, notochord is present only in larval tail.

Pharynx is perforated by gill slits in chordates while gill slits are absent in non-chordates.

The most distinctive feature of echinoderms is the presence of water vascular system which helps in locomotion, capture and transport of food and respiration.

All single-celled eukaryotes are placed under kingdom Protista.

Members of phylum Porifera are commonly known as sponges.