Non-chordates

Non-chordates

Non-chordates are animals that do not possess a notochord, which is a flexible, rod-like structure found in chordates (animals with a backbone or a similar structure). This phylum consists of a small group of worm-like, marine species with an organ-system level of organization. They are the most abundant and diversified of all animals living or extinct.

Members of phylum Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata and Hemichordata fall under Non-chordates.

The general characteristic features of Non-Chordates are:

  • They are cylindrical, triploblastic, coelomate, or pseudocoelomate animals.
  • Respiration in these animals takes place through gills, trachea or body surface.
  • Most of the times, sexes cannot be distinguished among the members.
  • Modes of reproduction involve sexual and asexual
  • Fertilization is external, though internal fertilization also occurs in some species.
  • The body of non-chordates generally includes an open type of circulatory system.

Phylum Ctenophora: Definition, Characteristics, Classification and Examples

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Definition, Characteristics, Classification and Examples of Phylum Ctenophora

Phylum Ctenophora (Gr., kestos=comb; phoros=bearing) is a group of marine invertebrates commonly known as comb jellies. These organisms are characterized by their gelatinous bodies, biradial symmetry, and the presence of eight rows of ciliary plates (combs) that they use for locomotion. Unlike jellyfish, which belong to Phylum Cnidaria, ctenophores lack stinging cells (cnidocytes) and instead capture prey using sticky cells called colloblasts.

Coral Reefs: Definition, Types, Formation and Economic Importance

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Types of Coral Reefs

Coral colonies grow continuously in size by budding of polyps and often form extensive masses, known as coral reefs.

Polymorphism in Coelenterates

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Polymorphism in Coelenterates

Occurrence of more than one type of individuals in the same species, which differ in form and function, is known as polymorphism.

Aurelia aurita: Classification, Morphology and Life cycle

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External morphology diagram of Aurelia aurita

Aurelia aurita is easily recognised by its soft bell or umbrella-shaped body with four red or purple horseshoe-shaped gonads on its upper surface and four long and narrow oral lobes hanging downward from the lower surface.

Phylum Coelenterata: Definition, Characteristics, Classification and Examples

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Definition, Characteristics, Classification and Examples of Phylum Coelenterata

Phylum Coelenterata (Gr., koilos = hollow ; enteron = intestine), also known as Phylum Cnidaria, is a group of aquatic, mostly marine animals characterized by a simple body structure with a single opening serving as both mouth and anus. Members of this phylum have a diploblastic body (two tissue layers: ectoderm and endoderm) and radial symmetry. They possess specialized stinging cells called cnidocytes containing nematocysts, used for defense and capturing prey. Coelenterates exhibit two main body forms: the sessile polyp (e.g., Hydra) and the free-floating medusa (e.g., jellyfish). This phylum includes organisms like corals, sea anemones, and hydroids, playing important roles in marine ecosystems, such as reef-building.

Canal System in Sponges

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Sycon type of Canal System in Sponges

Inside the body of Sponges, the water current flows through a certain system of spaces collectively forming the canal system in sponges.

Phylum Porifera: Definition, Characteristics, Classification and Examples

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Phylum Porifera: Definition, Characteristics, Classification and Examples

Phylum Porifera is a group of simple, multicellular, aquatic animals commonly known as sponges. They are characterized by their porous body structure, which allows water to circulate through specialized channels, enabling them to filter-feed by extracting nutrients and oxygen from the water. Most sponges are marine, though some are found in freshwater. Porifera are among the most ancient animal groups, with a simple organization that makes them pivotal to understanding the evolution of multicellular organisms.

Reproduction in Paramecium

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Transverse Binary Fission type of reproduction in Paramecium

Reproduction in Paramecium takes place asexually by transverse binary fission and also by several kinds of nuclear reorganizations, such as conjugation, endomixis, autogamy, e.t.c. Under certain conditions of food and temperature, it undergoes encystment.

Paramecium- Classification, Locomotion, Nutrition, Osmoregulation

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Labelled diagram of Paramecium

Paramecium is commonly known as slipper animalcule. It’s body is slipper shaped measuring about 0.3 mm in length.

Phylum Protozoa- Definition, Characteristics, Classification and Examples

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Phylum Protozoa: Definition, Characteristics, Classification and Examples

Phylum Protozoa is a group within the kingdom Protista consisting of single-celled, eukaryotic organisms that can be free-living or parasitic. These organisms are characterized by their ability to move independently using structures such as cilia, flagella, or pseudopodia. Protozoa are diverse in form and function and can reproduce sexually or asexually. They are found in a variety of environments, including freshwater, marine, and soil habitats. Some protozoans are known to cause diseases in humans and other animals.