What is the difference between whales and dolphins?

Quick Answer

The most surprising fact about the difference between whales and dolphins is that dolphins are actually whales.

In scientific terms, all of these marine mammals belong to the order Cetacea. This order is split into two main suborders based on their mouth anatomy:

1. Mysticeti (Baleen Whales): Large whales like the Blue Whale that possess baleen plates for filtering food.
2. Odontoceti (Toothed Whales): Whales that possess teeth, which includes all dolphins, porpoises, and the Sperm Whale.

When people ask for the difference, they are usually comparing baleen whales against dolphins. The primary physical distinctions are that baleen whales are generally much larger, possess two blowholes, and filter-feed, while dolphins are smaller, have a single blowhole, and use teeth to catch prey.

Essential Facts

While they share the same ocean Habitat and evolutionary history, distinct anatomical and behavioral traits separate the colloquial “whale” (baleen whales) from dolphins.

Taxonomic Classification

• The Family Tree: Under the order Cetacea, dolphins are classified as Odontocetes (toothed whales). This means asking the difference between them is similar to asking the difference between a beagle and a dog—one is a category, the other is a specific type within that category.
• The Orca Paradox: The Killer Whale is technically the largest species of dolphin, yet it carries the name “whale,” further blurring the linguistic lines. You can read more about this in our guide: are orcas whales.

Anatomy and Physiology

• Blowholes: One of the easiest ways to tell them apart is the blowhole. Baleen whales have two blowholes (similar to human nostrils) located on top of their heads. Dolphins and other toothed whales possess only one blowhole.
• Mouth Structure:
  • Baleen Whales: Instead of teeth, they have fringed plates made of keratin called baleen. They use these to filter massive amounts of water for krill and plankton. See: what do whales eat.
  • Dolphins: They possess cone-shaped teeth designed for gripping slippery fish and squid. They do not chew their food but swallow it whole.
• Size: Generally, animals referred to as “whales” are significantly larger. The Blue Whale can reach 100 feet, whereas most dolphins range between 5 to 12 feet. However, the size distinction isn’t perfect, as some toothed whales (like the Sperm Whale) are massive.

Social Structure and Behavior

• Pod Life: Dolphins generally live in large, complex social groups called pods, sometimes numbering in the hundreds or thousands (superpods). While some baleen whales travel in groups, many, like the solitary Minke Whale, are more independent outside of breeding seasons.
• Communication: Dolphins rely heavily on echolocation for navigation and hunting, producing high-frequency clicks and whistles. Baleen whales produce lower-frequency sounds, including complex songs that can travel hundreds of miles underwater.
• Dorsal Fins: Most dolphins have a curved, sickle-shaped dorsal fin located near the center of their back. Baleen whales often have smaller humps or very small dorsal fins set further back on their bodies.

Learn More

Understanding the distinction between these animals helps in appreciating their unique adaptations and conservation needs.

• Classification: To dive deeper into how scientists organize these species, visit our guide on Classification.
• Anatomy: For a detailed look at physical traits like fins, flukes, and blowholes, check out Anatomy.
• Conservation: Both groups face threats from climate change and bycatch. Protecting their Habitat is crucial for the survival of the entire Cetacea order.
• Related Reading: If you are curious about specific classifications, you might ask are dolphins whales or investigate are killer whales dolphins.