Black-Lined Periwinkle vs common sea hare

Littorina saxatilis compared with Aplysia punctata

Taxonomic Classification

Rank	Black-Lined Periwinkle	common sea hare
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Mollusca (Mollusks)	Mollusca (Mollusks)
Class same	Gastropoda (Gastropoda)	Gastropoda (Gastropoda)
Order	Littorinimorpha (Littorinimorpha)	Aplysiida (Aplysiida)
Family	Littorinidae	Aplysiidae
Genus	Littorina	Aplysia
Species	Littorina saxatilis	Aplysia punctata

Evolutionary Relationship

Black-Lined Periwinkle and common sea hare share a common ancestor at the Class level: Gastropoda. (Gastropoda)

Conservation Status

Black-Lined Periwinkle

LC — Least Concern

common sea hare

LC — Least Concern

Physical Characteristics

Attribute	Black-Lined Periwinkle	common sea hare
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Black-Lined Periwinkle

Habitat

Found across multiple habitat types including tropical and subtropical grasslands and savannas, flooded grasslands and savannas, and deserts and xeric shrublands within the Afrotropic biogeographic realm.

Range

Widely distributed across Africa (Namibia, South Africa), Europe (5 countries), and North America (United States).

common sea hare

Habitat

Typically found in terrestrial and aquatic habitats including forests and freshwater.

Range

Distributed across Denmark, Norway, Portugal, and Sweden.

Black-Lined Periwinkle

The Black-Lined Periwinkle (Littorina saxatilis) is a species in the genus Littorina. It is currently classified as Least Concern on the IUCN Red List. Found across multiple habitat types including tropical and subtropical grasslands and savannas, flooded grasslands and savannas, and deserts and xeric shrublands within the Afrotropic biogeographic realm.

common sea hare

<em>Aplysia punctata</em>, the common sea hare, is a large opisthobranch sea slug in the family Aplysiidae, order Aplysiida, found in the northeastern Atlantic Ocean and Mediterranean Sea, with confirmed records from Denmark, Norway, Portugal, and Sweden. This species typically inhabits shallow subtidal and intertidal zones with abundant macroalgae, feeding primarily on red and green algae — a diet that influences the color of the defensive purple ink it secretes when threatened. <em>Aplysia punctata</em> is a simultaneous hermaphrodite, capable of acting as both male and female during mating, and often forms mating chains involving multiple individuals. It can reach considerable size among European opisthobranch species, though body dimensions vary considerably with age and feeding conditions. The species is classified as Least Concern by the IUCN, reflecting stable populations across its coastal range. Biological traits for this species remain poorly documented in the scientific literature, including precise average data on lifespan, body length, weight, and detailed seasonal dietary patterns, though its general herbivorous feeding on macroalgae is well established.

Shared Countries

Both species can be found in 4 countries:

🇩🇰 Denmark 🇳🇴 Norway 🇵🇹 Portugal 🇸🇪 Sweden