Zoology Notes
Vorticella (L.,vortex=whirl pool) is a microscopic, unicellular eukaryotic ciliate. It occurs as a sessile attached by a stalk to the substratum. Its body is almost bell-shaped or campanulate with a free anterior end surrounded by cilia. The commonest species is Vorticella campanula. Some of the species included in this genus … Read more
Aurelia is commonly referred to as jellyfish because it is made of a jelly-like substance. A jellyfish is not true fish which is a vertebrate animal with a backbone. It belongs to the class Scyphozoa of phylum Coelenterata. The most common scyphozoan jellyfish is Aurelia aurita (popularly known as moon … Read more
We know Arthropoda is the largest phylum, with the highest number of species, and the numbers of individuals are also high. So Arthropods have various types of respiratory systems, some of them described below : 1- Tracheal system 2- Book-lungs 3- Blood-gills 4- Gills 1. Tracheal Respiratory system It is … Read more
Euglena viridis (Gr.,eu, true+ glene, eyeball or eye pupil+L., Viridis, green) is a unicellular green organism with an eye-like photoreceptive structure. It is phytoflagellate as it possesses both chloroplasts as well as flagella. It is autotrophic in sunlight but becomes heterotrophic in dark. Systematic position Phylum: Protozoa Subphylum: Sarcomastigophora Superclass: … Read more
Hormones of Insects Body Although hormones are mainly present in chordates, yet some hormones are also present in arthropods, that is insects. There are various hormones secreted in insects, which play role in metamorphosis. Some of the hormones are as follows. 1- Brain hormone (BH) The brain has neurosecretory cells. … Read more
Hydra reproduces asexually by budding and sexually by the formation of gametes. Asexual reproduction of Hydra by Budding Figure: Hydra Budding. 1. Non-reproducing, 2. Creating a bud, 3. Daughter growing out, 4. Beginning to cleave, 5. Daughter broken off, 6. Daughter clone of the parent. Image Source: A.houghton19 (Wikimedia). Budding is a … Read more
Locomotion in Hydra Hydras are essentially sessile animals. They live attached by their pedal discs to objects in the water. Brown and green hydras can remain fixed at one spot for a considerable time, but green hydras often move about from place to place by several ingenious devices. They twist … Read more
Some insects are helpful for agriculture and human welfare but some insects are pests of our crop and some insects have poisonous nature. Here we study some beneficial and harmful importance of insects. A- Beneficial Insects 1- Insects and insects product in the food Insects are an abundant food supply … Read more
Parasitic adaptation of flatworms Adaption in parasites to survive in the environment of a body of the host is called parasitic adaptation. Mainly flat-worm are parasitic except Turbellaria, so they are adapted for parasitic nature. There are two types of parasitic adaptation to suit their parasitic mode of life. Morphological … Read more
Locomotory Organelles in Protozoa Protozoan shows different verities of locomotory organs, such as pseudopodia, pellicular contractile structure, flagella, cilia. 1. Pseudopodia Pseudopodia are false feet of some Sarcodina protozoans such as Amoeba. Pseudopodia are a temporary structure form by streaming of cytoplasm. It is comprised of ectoplasm and endoplasm both. Pseudopodia … Read more
Hydra are inconspicuous freshwater relatives of corals, sea anemones, and jellyfish that are classified under the phylum Cnidaria, Class Hydrozoa, Order Anthomedusae/Anthoathecata, and Family Hydroidea. It is essentially a sedentary organism living attached to stones, pebbles, and water plants, but can get released from the substratum and swim. The name … Read more
Wuchereria bancrofti is a filarial nematode that causes Wuchereriasis or filariasis(commonly called elephantiasis) in human beings. The name of this worm is given Wuchereria bancrofti in honor of the two scientists Wucherer and Bancroft who made a considerable contribution in studying the disease caused by these worms. Image Source: Study … Read more
Reproductive system of earthworm Earthworms do not reproduce asexually. Reproductive organs are somewhat complicated. The pheretima is monoecious or hermaphrodites having both male and female reproductive organs in the same individual. They cannot fertilize their own eggs because they are protandrous. Cross-fertilization occurs as a rule because of the relative … Read more
Nutrition of Amoeba proteus Food and selection of food Amoeba is carnivorous. It feeds by phagocytosis. The mode of nutrition is Zootrophic or holozoic. i.e. it requires ready-made (solid form) organic substances for food. The food consists of algal cells and filaments, bacteria, desmids, flagellates, ciliates, small metazoans such as … Read more
Classification of Amoeba proteus Phylum: Protozoa Subphylum: sacromastigophora Superclass: Sarcodina Class: Rhizopodea Subclass: Lobosia Order: Amoebida Genus: Amoeba Species: proteus Habit and Habitat of Amoeba proteus Amoeba proteus is widely distributed and commonly found on the bottom mud or on the underside of aquatic vegetation in freshwater, ponds, ditches, lakes, … Read more
Paramecium reproduces asexually by transverse binary fission and also undergoes several types of nuclear reorganization, such as conjugation, endomixis, autogamy, cytogamy, and hemixis, etc. 1. Transverse binary fission (Asexual reproduction) This is the commonest type of Asexual reproduction in Paramecium. It occurs during the favorable condition when food is available … Read more
1. Food Paramecium feeds in a holozoic manner, like an amoeba. The food comprises chiefly bacteria and minute protozoa which floats in the water in which it lives. It also feeds unicellular plants (algae, diatoms, yeasts, etc.) and small bits of animals and vegetables. Paramecium swims to a place where … Read more
Habit and Habitat Paramecium caudatum (Gr., paramekes=oblong+ L., caudata=tail) is a free-living organism which is one of the most common species of Paramecium having worldwide distribution. It is commonly found in freshwater, ponds, pools, ditches, streams, lakes, reservoirs, and rivers. It is usually found abundant in water containing decaying organic … Read more
The excretory organs are segmentally arranged, microscopic, coiled tubules called nephridia. Nephridia are ectodermal in origin. These are typically unbranched, and their inner ends open into coelom by a ciliated funnel, called nephrostome. A large number of small-sized nephridia are found in each segment which are called micronephridia and mesonephridia. … Read more