Correct Option
The correct option isOctopus
Explanation
Aquatic animals, particularly active swimmers, typically possess a streamlined body shape. This morphology tapers at both ends to minimize water resistance (drag) and facilitate rapid movement. However, organisms that primarily inhabit the seabed (benthic zone) or lead a sedentary lifestyle often lack this specific adaptation.
Option Analysis
- Shark: Incorrect. Sharks are active predators with a highly streamlined, torpedo-shaped body designed for speed and efficiency in the water column.
- Dolphin: Incorrect. Dolphins are marine mammals with a streamlined, fusiform body shape that allows them to swim at high speeds with minimal energy expenditure.
- Octopus: Correct. Octopuses are molluscs that typically inhabit the ocean floor (seabed). They possess a soft, bulbous body (mantle) and eight arms, lacking the rigid, streamlined shape found in fish or marine mammals. This body plan allows them to squeeze into tight crevices and camouflage effectively among rocks, rather than prioritizing continuous high-speed swimming.
- Whale: Incorrect. Whales are large marine mammals that possess a streamlined body to navigate the open ocean efficiently.
Key Takeaway: While most active marine swimmers (sharks, dolphins, whales) have streamlined bodies to reduce friction, benthic organisms like the octopus often lack this shape to facilitate maneuvering on the seabed and hiding in crevices.