The bodies of penguins are specially adapted for swimming. Their feet have webs, and their bodies are shaped in which way to help them move swiftly through water?

Introduction / Context:
Penguins are well known flightless birds that are excellent swimmers and divers. Their anatomy is adapted to life in water, where they chase fish and other prey. General science questions often focus on how body shape helps animals reduce friction and move efficiently through water or air. This question specifically asks about the term that best describes the body shape of penguins that helps them swim efficiently.

Given Data / Assumptions:

• The animal in the question is the penguin.
• We know that penguins are good swimmers with webbed feet.
• The options describe various possible body characteristics, such as heavy, feathery, streamlined, or oily.
• We assume knowledge of the term streamlined from basic physics and biology.

Concept / Approach:
A streamlined body is one that is smooth and tapered at both ends, reducing resistance when moving through a fluid such as air or water. Many aquatic animals, including fish, dolphins, and penguins, have streamlined bodies to minimise drag and conserve energy while swimming. Although penguins do have feathers and oily waterproof plumage, the key adaptation for reducing water resistance is their streamlined body shape. Therefore, the correct approach is to select the term that captures this hydrodynamic design.

Step-by-Step Solution:
Step 1: Recall that penguins are adapted for swimming in cold oceans and are efficient underwater hunters. Step 2: Remember that streamlined bodies are common in aquatic animals because they reduce friction and turbulence in water. Step 3: Observe that penguins have a tapered, torpedo like body that allows smooth movement through water. Step 4: Compare the options and identify streamlined as the term that describes this hydrodynamic shape. Step 5: Confirm that while penguins are feathery and have oily plumage, these words do not directly describe the shape of the body for swimming efficiency.

Verification / Alternative check:
A simple verification is to recall everyday examples of streamlined shapes, such as the design of ships, submarines, and even high speed trains and cars, which are smooth and tapered to reduce drag. Penguins show a similar pattern in nature. Their wings have evolved into flipper like structures and their body narrows toward the back. Textbooks in science explicitly mention that the streamlined shape of fish, dolphins, and penguins helps them move easily in water, confirming that streamlined is the correct answer.

Why Other Options Are Wrong:
Option A: Heavy refers to weight and not to shape. While penguins have dense bones, heaviness itself does not describe the body shape that aids swimming. Option B: Feathery only indicates that the body is covered with feathers and does not capture the aerodynamic or hydrodynamic shape. Option D: Oily describes how penguin feathers are coated with oil for waterproofing, but it does not refer to their overall body shape. Option E: Angular suggests sharp corners, which would actually increase drag in water rather than reduce it, so it is not an accurate description.

Common Pitfalls:
Learners sometimes focus too much on descriptive features such as feathers or oily coating, which are indeed important for insulation and waterproofing but do not answer the question about shape. Another mistake is to associate streamlined only with machines or vehicles and not with animals. To avoid confusion, remember that many aquatic animals and birds have streamlined bodies, meaning narrow at the ends and wider in the middle, which helps reduce resistance in water or air.

Final Answer:
Penguins have streamlined bodies, along with webbed feet, which helps them swim swiftly and efficiently in water.