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Organisms in this world are categorized into living and non-living organisms. Furthermore, living organisms are classified into vertebrates and invertebrates. Vertebrates are those groups of living organisms that have proper spinal structure whereas invertebrates do not have a spine and backbone.
Key Terms: Vertebrates, Invertebrates, Living Organisms, Chordata, Animal Kingdom
Explanation on Vertebrates
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Vertebrates are grouped under Chordata family. Furthermore, vertebrates are the strongest species of living organisms. This is due to the presence of proper spinal structure and the backbone. Human beings also come under the family of vertebrates. In human beings, the vertebra consists of 33 well-stacked bones that are finely interlocked with each other.
All Vertebrates that are grouped in the Chordata family have basic features. Vertebrates have a ventral muscular heart. Furthermore, the heart has chambers that are present 2, 3, or 4 in numbers in different organisms based on their functionality. Vertebrates have kidneys that facilitate the excretion process and also have an osmoregulation system.
Explanation on Invertebrates
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Invertebrates are stacked under the group of non-Chordata. They are called so due to the absence of notochord in them. The absence of notochord is due to the absence is a proper spinal structure in Invertebrates. The non-Chordata kingdom is classified into many groups like phylum hemichordate, Echinodermata, phylum Mollusca, etc. Earlier, phylum hemichordate was placed under Vertebrates or the Chordata groups but, if the recent categorization is to be considered, hemichordate comes under the non-Chordata group.
Difference Between Vertebrates and Invertebrates
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| Vertebrates | Invertebrates |
| Vertebrates have a proper spinal structure. | Invertebrates do not have a spine. |
| Notochord is present in vertebrates. | Notochord is absent in invertebrates. |
| Central Nervous System is characterized by features of dorsal, hollow, and single. | Central Nervous System is characterized by ventral, solid and double features. |
| Pharynx is present and is pierced by gill slits. | Gill slits are not present. |
| Heart is ventral. | Heart is dorsal if it is present. |
| Reproduction is of sexual type. | Reproduction is of asexual type. |
| There is a well-defined circulatory system in terms of arteries and veins. | Circulatory system is not defined and is of open type. |
| Organisms are of both warm-blooded and cold-blooded types. | Organisms are of cold-blooded type. |
| Some of the examples are mammals, birds, reptiles, amphibians, etc. | Some of the examples are insects, worms, arthropods, etc. |
Things to Remember
- Living organisms are classified into two forms: vertebrates and invertebrates.
- Vertebrates are those groups of living organisms that have proper spinal structure.
- Invertebrates are those living organisms that do not have a spine and the backbone is absent.
- Vertebrates are grouped under Chordata family.
- Invertebrates are stacked under group of non-Chordata.
Sample Questions
Ques. Compare the open circulatory system with the closed circulatory system. (2 marks)
Ans. In open circulatory system, blood flows via an open space that is called lacuna. Furthermore, in the open circulatory system, haemocoel is present. Blood flow is not regulated and is slow in velocity. In closed circulatory system, blood blows through closed blood vessels and hemocoel is absent. Furthermore, blood flow is regulated and has high velocity.
Ques. What are triploblastic animals? (2 marks)
Ans. Triploblastic animals are the animals that have the ectoderm, the mesoderm and the endoderm forming the germ layer. All the organisms that are multicellular in nature are triploblastic on nature.
Triploblastic Arrangement
Ques. What are diploblastic animals? (2 marks)
Ans. Organisms that have cells arranged in two layers of embryo i.e., internal endoderm and external ectoderm, are called diploblastic animals. An, e.g., of a diploblastic organism is coelenterates.
Diploblastic Arrangement
Ques. Explain the significance of feathers in birds. (3 marks)
Ans. Feathers play a vital role in characterizing the bird species. Following are the significance of the feathers:
- Feathers control the flight of the birds.
- Feathers help in camouflaging the birds from their predators.
- In certain species of birds, the aesthetic nature of the feathers plays the role of sexual dimorphism.
- Feathers play a big role in protecting the birds from extreme climatic conditions. Furthermore, feathers also protect the eggs and the baby birds from undue external threats.
- For birds like owls, feathers play a balancing part while walking.
Ques. Classify the classes of vertebrates with two, three, and four-chambered hearts. (3 marks)
Ans. Organisms having a two-chambered heart contain one auricle and one ventricle. E.g., fish.
Organisms having a three-chambered heart have two auricles and one ventricle. E.g. amphibians.
Organisms having a four-chambered heart contain two auricles and two ventricles. E.g., mammals.
Classes of Vertebrates
Ques. Explain bioluminescence by citing an example. (3 marks)
Ans. Bioluminescence is process in which organisms emit or radiate light. Furthermore, process of bioluminescence occurs due to chemical reactions that occur in body of organisms. Bioluminescence is a mechanism that is used by a certain organism to warn predators and also forms a channel of communication between members. Many aquatic and marine living organisms exhibit bioluminescence.
Ques. What are the differences between vertebrates and invertebrates? Explain in detail. (5 marks)
Ans. Following are some of the key differences between vertebrates and invertebrates:
| Vertebrates | Invertebrates |
| Vertebrates have a proper spinal structure. | Invertebrates do not have a spine. |
| The notochord is present in vertebrates. | The notochord is absent in invertebrates. |
| Central Nervous System is characterized by the features of dorsal, hollow, and single. | Central Nervous System is characterized by the features of ventral, solid and double. |
| The pharynx is present and is pierced by gill slits. | Gill slits are not present. |
| The heart is ventral. | The heart is dorsal if it is present. |
| Reproduction is of sexual type. | Reproduction is of asexual type. |
| There is a well-defined circulatory system in terms of arteries and veins. | The circulatory system is not defined and is of open type. |
| The organisms are of both warm-blooded and cold-blooded types. | The organisms are of cold-blooded type. |
| Some of the examples are mammals, birds, reptiles, amphibians, etc. | Some of the examples are insects, worms, arthropods, etc. |
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