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Kingdom Classification - Classification of Animals (Invertebrates and Vertebrates)

Grade 7ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Kingdom Animalia consists of multicellular, eukaryotic organisms that follow a heterotrophic mode of nutrition.

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The primary basis of classification in the animal kingdom is the presence or absence of a vertebral column (backbone). Animals are divided into Invertebrates and Vertebrates.

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Invertebrates (Non-chordates) lack a backbone. Major phyla include PoriferaPorifera (sponges), CnidariaCnidaria (jellyfish), PlatyhelminthesPlatyhelminthes (flatworms), NematodaNematoda (roundworms), AnnelidaAnnelida (segmented worms), ArthropodaArthropoda (insects/crustaceans), MolluscaMollusca (snails), and EchinodermataEchinodermata (starfish).

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Vertebrates (Chordates) possess a vertebral column and a closed circulatory system. They are classified into five classes: PiscesPisces, AmphibiaAmphibia, ReptiliaReptilia, AvesAves, and MammaliaMammalia.

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Body temperature regulation is a key distinguishing factor: PoikilothermicPoikilothermic (cold-blooded) animals cannot regulate internal temperature, while HomeothermicHomeothermic (warm-blooded) animals maintain a constant internal temperature.

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Scientific nomenclature follows the Binomial system, usually written in italics or underlined, such as Homo sapiensHomo\ sapiens.

📐Formulae

Invertebrates  ⟹  No Notochord/Vertebral Column\text{Invertebrates} \implies \text{No Notochord/Vertebral Column}

Vertebrates  ⟹  Dorsal Nerve Cord+Vertebral Column\text{Vertebrates} \implies \text{Dorsal Nerve Cord} + \text{Vertebral Column}

Tbody∝Tenvironment (for Poikilotherms)T_{body} \propto T_{environment} \text{ (for Poikilotherms)}

Tbody=constant≈37∘C (for Humans in Class Mammalia)T_{body} = \text{constant} \approx 37^\circ C \text{ (for Humans in Class Mammalia)}

💡Examples

Problem 1:

Identify the Phylum of an animal that has a soft unsegmented body, a muscular foot for locomotion, and often a hard calcareous shell.

Solution:

Phylum MolluscaMollusca.

Explanation:

Mollusks are characterized by soft bodies, a mantle, and a muscular foot. Common examples include PilaPila (Apple Snail) and OctopusOctopus.

Problem 2:

An organism is found to be cold-blooded, breathes through both lungs and moist skin, and requires water for laying eggs. To which class of Vertebrates does it belong?

Solution:

Class AmphibiaAmphibia.

Explanation:

Amphibians like Rana tigrinaRana\ tigrina (Frog) exhibit dual life (land and water), have moist skin for respiration (cutaneouscutaneous respiration), and undergo external fertilization in water.

Problem 3:

Which is the largest Phylum in the animal kingdom, and what is its defining characteristic?

Solution:

Phylum ArthropodaArthropoda.

Explanation:

Arthropods make up about 80%80\% of all known animal species. Their defining characteristic is the presence of jointed appendages and a chitinous exoskeleton.

Classification of Animals (Invertebrates and Vertebrates) Revision - Class 7 Science ICSE