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Classification - Vertebrates and Invertebrates

Grade 6Cambridge (IGCSE)

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

🔑Concepts

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Classification is the process of sorting living things into groups based on shared characteristics, primarily using the system developed by Carl Linnaeus.

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Animals are divided into two main groups: Vertebrates (with a backbone) and Invertebrates (without a backbone).

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Vertebrates belong to the Phylum Chordata and are divided into five classes: Fish, Amphibians, Reptiles, Birds, and Mammals.

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Invertebrates make up about 95%95\% to 97%97\% of all animal species. Major groups include Arthropods, Molluscs, Annelids, and Cnidarians.

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Arthropods are characterized by having an exoskeleton made of chitin, segmented bodies, and jointed legs.

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Respiration in these animals involves the exchange of gases: taking in O2O_2 and releasing CO2CO_2.

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Binomial Nomenclature is the formal system of naming species using two parts: the Genus (capitalized) and the species (lowercase), usually written in italics, e.g., PantheraPanthera leoleo.

📐Formulae

C6H12O6+6O2→6CO2+6H2O+Energy (ATP)C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy (ATP)}

Total Species=Vertebrates+Invertebrates\text{Total Species} = \text{Vertebrates} + \text{Invertebrates}

Percentage of Invertebrates=Number of Invertebrate SpeciesTotal Animal Species×100\text{Percentage of Invertebrates} = \frac{\text{Number of Invertebrate Species}}{\text{Total Animal Species}} \times 100

💡Examples

Problem 1:

An unknown animal is discovered. It has moist skin, no scales, lays eggs in H2OH_2O, and lives both on land and in water. Classify this animal and name its class.

Solution:

The animal is a Vertebrate belonging to the class Amphibians.

Explanation:

Amphibians are characterized by their 'double life' (metamorphosis), moist skin for gas exchange, and the requirement of H2OH_2O for external fertilization and egg-laying.

Problem 2:

Identify the group of invertebrates that possess an exoskeleton, three body segments (head, thorax, abdomen), and 33 pairs of jointed legs.

Solution:

The group is Insects (a class within the Phylum Arthropoda).

Explanation:

Insects are defined by the specific arrangement of 66 legs (3 pairs) and a body divided into three distinct regions, protected by a hard chitinous exoskeleton.

Problem 3:

Distinguish between 'Ectothermic' and 'Endothermic' animals in terms of body temperature (TT).

Solution:

Ectotherms: Tbody≈TenvironmentT_{body} \approx T_{environment}. Endotherms: Tbody=ConstantT_{body} = \text{Constant}.

Explanation:

Ectotherms (like reptiles) rely on external heat sources to regulate body temperature, whereas endotherms (like mammals and birds) use internal metabolic heat to maintain a stable TT regardless of the environment.