Month: May 2021

Earthquakes- definition, related facts

pcsclasses
Earthquakes- definition, related facts

Earthquakes (also called quakes, tremors, or temblors) A sudden movement of Earth’s crust is caused by the release of stress accumulated along geologic faults or by volcanic activity. In simple words, the earthquake refers to the shaking of the earth. Mainly it is a natural event caused due to release of energy and generates waves that travel in all directions. We can say that an earthquake is a series of shocks and tremors resulting from the sudden release of pressure along active faults and in areas of volcanic activity. Important…

Read More

Phylum-Hemichordata

pcsclasses
Phylum-Hemichordata

Phylum-Hemichordata These are recently added as a phylum under non-chordates, earlier these were considered as a sub-phylum under the phylum chordates. They possess a rudimentary structure in the collar region known as a stomochord, which is similar to a notochord in structure. The hemichordates are marine deuterostome animals, generally considered the sister group of echinoderms. They appeared in the lower middle of the Cambrian. Scientific classification of phylum hemichordate Scientific classification of phylum hemichordata Kingdom: Animalia Subkingdom: Eumetazoa Clade: ParaHoxozoa Clade: Bilateria Clade: Nephrozoa Superphylum: Deuterostomia Clade: Ambulacraria Phylum: Hemichordata…

Read More

Phylum-Echinodermata

pcsclasses
Phylum-Echinodermata

Phylum-Echinodermata The members of Phylum Echinodermata are exclusively marine animals, till now these are not found as terrestrial or freshwater. About seven thousand living species are included in this phylum. The adults are recognizable by their radial symmetry. The Phylum includes starfish, sea urchins, sand dollars, and sea cucumbers, as well as sea lilies or “stone lilies. The Echinoderms are the largest phylum that has no freshwater or terrestrial members. Characteristics features of Echinoderms Phylum-Echinodermata consists of the following characteristic features: These are spiny bodies and have an endoskeleton of…

Read More

Phylum-Mollusca

pcsclasses
Phylum-Mollusca

Phylum-Mollusca Phylum Mollusca is the second-largest phylum of the animal kingdom after the Arthropod. These are soft-bodied animals. The members of this phylum are called mollusks or mollusks. Around 85000 species of mollusks are recognized. The size of mollusks ranges from microscopic to 20 meters long animals. They show much impact on human lives. These are huge sources of food as well as ornaments. Characteristics features of phylum Mollusca Habitats: The mollusks exist on terrestrial or aquatic (marine or fresh-water habitats). Phylum Mollusca is the largest marine phylum. Level of…

Read More

Phylum-Arthropoda

pcsclasses
Phylum-Arthropoda

Phylum-Arthropoda – (The name is derived from- Atheros-joint, pods-appendages). These are invertebrates include insects, arachnids, myriapods, and crustaceans. Phylum Arthropoda is the largest phylum of the kingdom Animalia. Around two-thirds of all species on earth belongs to the phylum Arthropoda. Characteristics features of phylum Arthropoda Level of organization: The members having the organ-system level of organization. Symmetry: Bilateral symmetry in organisms Germinal layer: Triploblastic Segmented body Body cavity or coelom: These are coelomate animals. Exoskeleton: In arthropods, the body is covered with a chitinous exoskeleton. Body: The body of the…

Read More

Phylum-Annelida 

pcsclasses
Phylum-Annelida 

Phylum-Annelida – (Name Annelida: Latin word, annulus: little ring) Phylum-Annelida – The organisms of this phylum also known as the ringed worms or segmented worms, are a large phylum. The phylum includes over 22,000 extant species. The variation includes ragworms, earthworms, and leeches. They can survive in marine environments, freshwater, and other terrestrial environments. Characteristics features of Annelids Habitats: The members of this phylum annelida may be aquatic (i.e. marine and freshwater), or terrestrial, free-living, and in some members, parasitism is also found. Level of organization: in annelids the organ-system…

Read More

Phylum Platyhelminthes

pcsclasses
Examples of Platyhelminthes

Phylum Platyhelminthes (Greek; platys= Flat; helmins = worms); The flatworms. Phylum Platyhelminthes includes 13000 species. These are found as free-living as well as parasitic life forms. These are also called Flatworms because of having a dorso-ventrally flattened body. Characteristics features of Phylum Platyhelminthes The Platyhelminthes are mostly parasitic and live on or inside the host. A few are free-living and aquatic. The body of flatworms is thin, soft, unsegmented, and dorsoventrally flattened. They may be leaf-like or ribbon-like animals. These are mostly endoparasites, found in various animals including human beings.…

Read More

Phylum- Ctenophora

pcsclasses
Phylum - Ctenophora

Phylum- Ctenophora Ctenophora- singular ctenophore. These are commonly called sea walnuts or comb jellies or Venus’s girdles. Phylum Ctenophorehas a wide range of body forms, including the flattened, deep-sea Platyctenids,  in which the adults of most species lack combs, and the coastal beroids, which lack tentacles and prey on other ctenophores by using huge mouths armed with groups of large, stiffened cilia that act as teeth. Characteristics features of Ctenophora: Habitats: The members of Ctenophora are exclusively marine. Level of Organisation: Tissue level of organization. Germinal layer– Dipoloblastic organisms. Symmetry: The body is radially…

Read More

Phylum – Coelenterata (Cnidaria)

pcsclasses
example of coelenterata

Phylum – Coelenterata (Cnidaria) The name Cnidaria- is derived from the word cnidoblast or cnidocytes which contains stinging capsules or nematocytes. This phylum is a group of aquatic or marine organisms. The members of Coelenterata are found in colonies or solitary. Over 11,000 species are found. Chareceristic feature of coelentrates:  Habitats: They are aquatic, mostly marine, Free-living, or maybe sessile. Body symmetry: These are radially symmetrical animals. Level of organization: They exhibit a tissue level of organization. Diploblastic i.e. the cell found in two embryonic layers as external ectoderm and…

Read More

List of Important Glaciers of Himalayan Mountain

pcsclasses
Important Glaciers

List of Important Glaciers of Himalayan mountain The Glaciers are reservoirs of freshwater. They are formed from a mass of compacted recrystallized snow with the ability to flow. In simple words, a glacier is a huge mass of ice that moves slowly over land. As per National Snow & Ice Data Center, it occupies the world’s 10 % area. Here we have listed some important mountain glaciers of India which are relevant to the examination. List of Glaciers given in the table: Name of Glaciers Location Siachen Glacier The largest…

Read More