Tag: animal classification and its benefits

Autotrophy is the ability of organisms to synthesise their own food from inorganic materials using light or chemical energy. This is seen in all green plants, some bacteria and algae. Animals, however, have a heterotrophic mode of nutrition. They acquire their food from other organisms. Animals, therefore, do not show autotrophy. 

Multicellular animals have a dominant diploid life cycle (diplontic cycle) with the haploid generation reduced to the egg and sperm. The branches Radiata and Bilateria both include multicellular organisms, with Bilaterians a step more advanced than Radiata in multicellular complexity. Therefore both exhibit a diploid dominant life cycle. 

The subkingdom Parazoa includes multicellular organisms having less-specialized cells than in the Metazoa. It includes the phylum Porifera (sponges) and the organisms under this phylum lack tissues with a mass of cell embedded in a gelatinous matrix. Jellyfishes belong to the phylum Cnidaria and they do not belong to this subkingdom. 

Acellular word was given by Dobell and Hyman. Acellular is described as tissues or organisms that are not made up of separate cells but often have more than one nucleus and made up of proteins e.g., virus. Hence option A is correct.

Aristotle classified the animals into two groups, 'Anima' (animals with no red blood, invertebrates) and 'Enaima' (animals with red blood, vertebrates). 'Enaima' was further divided into 'Ovipara' and 'vivipara'. 

Deuterostomes are groups of animals that have true body cavities, in which the anus develops from the first opening in the embryo and the mouth develops later. All chordates are deuterostomes.

Animals are multicellular, eukaryotic organisms. All animals are heterotrophs, i.e., they can not synthesize their own food and depend on other organism for food.

Heterotrophs are organisms that obtain their food from other organisms as they cannot produce their own food. In food chains, they are usually secondary or tertiary consumers. The heterotroph hypothesis states that the first living organism was a heterotroph. It also assumed that the anaerobic heterotrophs evolved first.

Pennatula (sea fan) belongs to the Phylum Cnidaria and class Anthozoa. Beroe (comb jelly) belongs to the phylum Ctenophora. Monocystis belongs to the phylum Protozoa and class Telospora. Wuchereria belongs to Aschelminthes. Cliona belongs to the Porifera phylum and class demospongiae. 

• Rotifers are multicellular, microscopic and free-living microscopic or near-microscopic multicellular pseudocoelomate animals. Hence multicellular nature and small size
• .They belong to the phylum Rotifera
• They are characterized by having specialized organ systems and a complete digestive tract that includes both a mouth and anus. Since these characteristics are all uniquely animal characteristics, rotifers are recognized as animals or metazoans, even though they are microscopic.
  
• Rotifers are called wheel animalcules because their corona is composed of several ciliated tufts around the mouth i.e ring of cilia, that in motion resemble a wheel. Hence Characteristic of rotifers is small size, ring of cilia and multicellular nature.
• So, the correct answer is 'All the above'.