Which one of the following pairs of animals consists entirely of warm blooded (endothermic) animals that maintain a nearly constant body temperature?

Introduction / Context:
Animals can be categorised as warm blooded (endothermic) or cold blooded (ectothermic) based on how they regulate body temperature. Warm blooded animals maintain a relatively constant internal temperature, while cold blooded animals rely heavily on external conditions. This question tests whether you can correctly identify a pair in which both animals are warm blooded according to biological classification.

Given Data / Assumptions:

• Warm blooded animals include birds and mammals, which regulate body temperature internally.
• Cold blooded animals include most fishes, amphibians, and reptiles.
• The pairs given are:
  • Crocodile and Ostrich
  • Hagfish and Dogfish
  • Tortoise and Ostrich
  • Peacock and Camel
• We assume standard textbook definitions of endothermy and ectothermy.

Concept / Approach:
Birds (class Aves) and mammals (class Mammalia) are warm blooded animals. Reptiles (including crocodiles and tortoises) and fishes (including hagfish and dogfish) are cold blooded. Therefore, to find the correct pair, we need a pair where both animals are either birds or mammals. Peacock is a bird, and camel is a mammal, so that pair contains two warm blooded animals. The other pairs each include at least one cold blooded animal and therefore are not completely warm blooded.

Step-by-Step Solution:
Step 1: Identify the thermoregulatory status of each animal. Birds and mammals are warm blooded; reptiles and fishes are cold blooded. Step 2: Examine Option A, Crocodile and Ostrich. Crocodile is a reptile (cold blooded), while ostrich is a bird (warm blooded), so the pair is mixed. Step 3: Examine Option B, Hagfish and Dogfish. Both are fishes and therefore cold blooded. Step 4: Examine Option C, Tortoise and Ostrich. Tortoise is a reptile (cold blooded), ostrich is a bird (warm blooded), so again a mixed pair. Step 5: Examine Option D, Peacock and Camel. Peacock is a bird and camel is a mammal; both groups are warm blooded, so this pair fully satisfies the condition.

Verification / Alternative check:
A quick verification method is to remember a simple rule: among the vertebrates, only birds and mammals are classically considered warm blooded. Therefore, any pair consisting entirely of birds, entirely of mammals, or a mix of birds and mammals will be fully warm blooded. When you scan the options, only Peacock (bird) and Camel (mammal) fit this rule. The other pairs include reptiles or fishes, which are cold blooded and immediately disqualify those options from being fully warm blooded pairs.

Why Other Options Are Wrong:
Crocodile and Ostrich is wrong because crocodile is a reptile and therefore cold blooded, so the pair is not entirely warm blooded. Hagfish and Dogfish is incorrect because both animals are fishes, and fishes are cold blooded. Tortoise and Ostrich is also wrong because tortoise is a reptile and not warm blooded. These options all mix warm and cold blooded animals or include only cold blooded species, contradicting the requirement of a fully warm blooded pair.

Common Pitfalls:
Students sometimes get confused by the large body size of reptiles such as crocodiles and mistakenly think they might be warm blooded. Another pitfall is to focus on habitat (land or water) rather than on taxonomic class. Some may also misremember hagfish or dogfish as unusual mammals, but they are in fact fishes. To avoid such errors, always tie warm bloodedness to birds and mammals and treat reptiles, amphibians, and fishes as cold blooded unless you are studying special advanced exceptions. This clear rule helps you quickly pick Peacock and Camel as the correct pair.

Final Answer:
The correct pair is Peacock and Camel, because both are warm blooded animals that maintain a relatively constant body temperature.