Introduction of Non-chordates
Dr. Mahesh Pentewar
Associate Professor
Gramin ACS Mahavidyalaya
Vasantnagar, Kotgyal
Tq. Mukhed Dist. Nanded
Introduction of Non-chordates�
Invertebrate
Introduction of Non-chordates�
2)Numerical strength: At present nearly one million living species of animals are known, out of which about 95% constitute the invertebrates.
3)Shape: All the shapes are including irregular, plant like, ribbon shaped, flat worms, elongated, vermiform, star, shaped global, rounded, etc. occur.
Invertebrate
Introduction of Non-chordates
4)Size: It consist from microscopic Protozoan to large sized Cephalopods, Giant squids of North Atlantic, Architeufhis has been reported to have attained a total body length of 16.5 meters including the tentacles.
Invertebrate
Introduction of Non-chordates
5)Symmetry: Invertebrates represents all the types of symmetries. Protozoans show bilateral as well as radial symmetry. Some are asymmetrical. Sponges are either asymmetrical or radially symmetrical. Coelenterates are radially symmetrical. Some have spherical symmetry.
Invertebrate
Introduction of Non-chordates
6)Grades of origination: Invertebrates shows all grades of organization. Acellular grade or protoplasmic grade is seen, tissue grade is observed in coelenterates. The tissue organ grade is occurring in flat worms. The organ system grade organization is characteristic of all higher invertebrates.
Invertebrate
Introduction of Non-chordates
7) Germ Layer: Germ layers are absent in Protozoa due to it’s unicellularity. All other invertebrates are either diploblastic (Porifera and Coelenterata); or triploblastic having three body layers i.e. ectoderm, endoderm and mesoderm (other invertebrates).
8) Integument: In protozoa, body covering is a delicate plasma membrane, while some have pellicle, single layered epidermis, in others are non cellular cuticle or chitinoid covering (Arthropoda).
Invertebrate
Introduction of Non-chordates
9) Locomotory organs: Some animals are sessile, such as sponges and corals, Protozoa move by pseudopodia, flagella and cilia. Coelenterates and Mollusca shows tentacular movements. Annelids move by setae, parapodia and suckers. Arthropodes move with jointed legs. Echinoderm moves with arms contain tube feet.
Invertebrate
Introduction of Non-chordates
10)Segmentation: Certain flatworms shows pseudosegmentation. Segmentation is found in Annelia and Arthropoda.
Invertebrate
Introduction of Non-chordates
11) Endoskeleton: The invertebrates animal do not possess any kind of rigid internal skeleton to give support to the body and provide surface for attachment of muscles. Many invertebrates are soft bodied, while some like Arthropodes and Molluscs, possess hard exoskeleton for supporting and protecting their body.
Invertebrate
Introduction of Non-chordates
12) Coelom: Protozoans are coelomate. In sponges and coelenterates, the body is double layered sac surrounding a single cavity, which opens to the outside through a mouth. Such a animals are acoelomate, as they no coelom. Other invertebrates possess a cavity in between the body wall and the gut. This cavity is called as pseudocoelom in nematodes, not lined by mesoderm. In higher invertebrates, the true coelom is present.
Invertebrate
Introduction of Non-chordates
13) Dorsal gut: Alimentary canal is either absent or incomplete, or if present, it lies dorsal to the nerve cord runs from mouth up to the anus.
14) Digestion: In Protozoa and Porifera the digestion is intra cellular. In Coelenterate digestion is intra as well as extracellular. All other invertebrates shows extracellular digestion.
Invertebrate
Introduction of Non-chordates
15) Circulatory system: It is well developed in higher invertebrates. Some like Arthropodes and Molluscs, possess open or lacunar circulatory system, while in other the blood flows in closed vessels; i.e. closed circulatory system. Heart is dorsal to the gut.
Invertebrate
Introduction of Non-chordates
16) Respiratory system: Protozoans, Sponges, Coelenterates and many worms have a direct diffusion of gases between the body surface and environment. Gills are common in most higher invertebrates. Echinoderms possess branchiae and tube feet, sea cucumber have respiratory tree, In insects the tracheal system is adapted for aerial respiration, pulmonary lungs are occur in Mollusca, book lungs in Arthropoda.
Invertebrate
Introduction of Non-chordates
17) Excretory system: In Protozoans, Sponges, Coelenterates excretion occurs by direct diffusion through cell membranes. Flatworms have flame cells. Annelida and Molluscs contain true nephridia, malpighian tubules in Arthropoda. Echinoderms and some other invertebrates have amoeboid cells or phagocytes for storage and disposal of excretory products to the outside.
Invertebrate
Introduction of Non-chordates
18) Nervous system: In lower invertebrates, Coelenterates, nervous system is represented by a ring of nerve tissue. In bilaterally symmetrical invertebrates, nerve cord running along midventrally. The nerve ring and nerve cords bear ganglia. In higher invertebrates, the head ganglia from the brain. Invertebrate nervous system is characterized by solid nerves.
Invertebrate
Introduction of Non-chordates
19) Simple sense organs: In Protozoans, the whole of the protoplasm acts as a receptor, while in flagellates, the stigma or eyespot acts as a photoreceptor. Some possess statocysts for equilibrium and sensory pits for chemoreception. Annelids also have simple eyes. In Arthropods compound eyes are found with simple eyes, tentacle receptors and chemoreceptors are common in Arthropods and Molluscs.
Invertebrate
Introduction of Non-chordates
20) Reproduction: They show asexual binary fission up to the sexual reproduction type. Parthenogenesis is also found in some cases. Fertilization either internal or external. Development is direct or indirect.
21) Cold blooded animals: All the invertebrates are cold blooded.
Invertebrate
Invertebrate