Final answer:
The statement that some aquatic poikilotherms, such as sharks, can maintain a higher internal body temperature than the surrounding water is true. Certain species exhibit warm-blooded adaptations that allow them to regulate their body temperature internally, despite being typically classified as ectotherms.
Step-by-step explanation:
The student has asked whether some aquatic poikilotherms, such as sharks, can maintain a higher internal body temperature than the surrounding water. The main answer to this question is true. Some species of sharks, along with tuna and swordfish, have adaptations that allow them to raise their body temperature above that of their environment. This is an exception to the common trait of ectothermic fish, which typically have a body temperature that depends on their surroundings. These unique poikilotherms use internal mechanisms to generate heat, bypassing the usual limitations of an ectothermic metabolism in cooler environments.
It is important to understand that while many ectotherms are known as 'cold-blooded', some can maintain or even elevate their body temperatures through behaviors like basking in the sun or through physiological adaptations. Examples of such adaptations are the presence of heat exchangers or increased metabolic heat production. These exceptional species demonstrate that the classification of animals into endotherms and ectotherms, though useful, has its exceptions and that nature often presents a diverse range of survival strategies.