Colonial tunicate vs Common Seal

Symplegma reptans compared with Phoca vitulina

Key Differences

• Colonial tunicate is Not Evaluated while Common Seal is Near Threatened.

Taxonomic Classification

Rank	Colonial tunicate	Common Seal
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Ascidiacea (Ascidiacea)	Mammalia (Mammals)
Order	Stolidobranchia (Stolidobranchia)	Pinnipedia (Seals & Sea Lions)
Family	Styelidae	Phocidae (True Seals)
Genus	Symplegma	Phoca (Harbor Seals)
Species	Symplegma reptans	Phoca vitulina

Evolutionary Relationship

Colonial tunicate and Common Seal share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Colonial tunicate

NE — Not Evaluated

Common Seal

NT — Near Threatened

Population: ~500.0K

Trend: Stable →

Physical Characteristics

Attribute	Colonial tunicate	Common Seal
Diet	—	Carnivore
Average Lifespan	—	30 years
Average Length	—	1.7 m
Average Weight	—	80.0 kg

Habitat & Geographic Range

Colonial tunicate

Habitat

Native to Europe and North America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Mexico, Norway, Sweden, and United States.

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.

Colonial tunicate

<em>Symplegma reptans</em> is a colonial tunicate in the family Styelidae with known occurrences in Mexico, Norway, Sweden, and the United States. This species has not been evaluated by the IUCN. Colonial tunicates in the genus <em>Symplegma</em> form encrusting sheet-like colonies on hard marine substrates, including rocks, shells, and artificial structures, in shallow coastal environments. Each colony is composed of multiple filter-feeding zooids embedded in a common tunic, through which nutrients and metabolites are distributed. The presence of <em>Symplegma reptans</em> across both the North Atlantic and Pacific coastal regions suggests either a wide native distribution or a history of introduction through maritime vectors such as ballast water and hull fouling. As a sessile filter feeder, this species contributes to water column filtration and nutrient cycling within benthic communities. The reproductive biology of <em>Symplegma reptans</em> likely involves both sexual reproduction via larval dispersal and asexual proliferation through budding within established colonies. Biological traits of this species remain poorly documented in the scientific literature.

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.

Shared Countries

Both species can be found in 3 countries:

🇳🇴 Norway 🇸🇪 Sweden 🇺🇸 United States