Common Seal vs Leatherback Sea Turtle

Phoca vitulina compared with Dermochelys coriacea

Key Differences

• Common Seal is Near Threatened while Leatherback Sea Turtle is Vulnerable.
• Leatherback Sea Turtle is 6.2x heavier than Common Seal.
• Leatherback Sea Turtle lives longer (50 years vs 30 years).

Taxonomic Classification

Rank	Common Seal	Leatherback Sea Turtle
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Mammalia (Mammals)	Reptilia (Reptiles)
Order	Pinnipedia (Seals & Sea Lions)	Testudines (Turtles & Tortoises)
Family	Phocidae (True Seals)	Cheloniidae (Sea Turtles)
Genus	Phoca (Harbor Seals)	Chelonia (Green Sea Turtles)
Species	Phoca vitulina	Dermochelys coriacea

Evolutionary Relationship

Common Seal and Leatherback Sea Turtle share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Common Seal

NT — Near Threatened

Population: ~500.0K

Trend: Stable →

Leatherback Sea Turtle

VU — Vulnerable

Population: ~35.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Common Seal	Leatherback Sea Turtle
Diet	Carnivore	Carnivore
Average Lifespan	30 years	50 years
Average Length	1.7 m	2.0 m
Average Weight	80.0 kg	500.0 kg

Habitat & Geographic Range

Common Seal

Habitat

Typically found in diverse ecosystems where prey species are available.

Range

Found across Europe (7 countries) and North America (United States). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Leatherback Sea Turtle

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and tropical and subtropical grasslands and savannas, among 5 distinct biome types spanning the Australasia and Indomalayan and Neotropic realms. Populations are also found in montane and highland environments at higher elevations.

Range

Distributed across Costa Rica, Indonesia, Malaysia, and Trinidad and Tobago. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Common Seal

The most widely distributed pinniped, harbor seals inhabit temperate and subarctic coastal waters of both the North Atlantic and North Pacific. Adults reach up to 130 kg and spend roughly equal time at sea hunting fish, squid, and crustaceans and hauling out on beaches or rocks to rest. Their large, expressive eyes are adapted for underwater vision in low light. Harbor seals are a critical food source for orcas, sharks, and polar bears.

Leatherback Sea Turtle

The leatherback is the largest living turtle and the fourth-heaviest reptile. Unlike other turtles, it has a soft, leathery shell.