Bigeye thresher vs common arm squid

Alopias pelagicus compared with Brachioteuthis riisei

Key Differences

• Bigeye thresher is Endangered while common arm squid is Data Deficient.

Taxonomic Classification

Rank	Bigeye thresher	common arm squid
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Chordata (Chordates)	Mollusca (Mollusks)
Class	Chondrichthyes (Cartilaginous Fish)	Cephalopoda (Cephalopods)
Order	Lamniformes (Mackerel Sharks)	Oegopsida (Oegopsida)
Family	Alopiidae	Brachioteuthidae
Genus	Alopias	Brachioteuthis
Species	Alopias pelagicus	Brachioteuthis riisei

Evolutionary Relationship

Bigeye thresher and common arm squid share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Bigeye thresher

EN — Endangered

common arm squid

DD — Data Deficient

Physical Characteristics

Attribute	Bigeye thresher	common arm squid
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Bigeye thresher

Habitat

Typically found in marine environments from coastal waters to deep ocean.

Range

Distributed across Colombia and Taiwan. Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

common arm squid

Habitat

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

Range

Distributed across Chile and Norway.

Bigeye thresher

The Bigeye thresher (Alopias pelagicus) is a species in the genus Alopias. It is currently classified as Endangered on the IUCN Red List. Typically found in marine environments from coastal waters to deep ocean.

common arm squid

<em>Brachioteuthis riisei</em>, commonly known as the Common Arm Squid, is a cephalopod mollusk in the family Brachioteuthidae. This species is classified as Data Deficient on the IUCN Red List, reflecting significant gaps in knowledge about its population size, ecology, and distribution. Records of this species have been reported from waters off Chile and Norway, suggesting a broad oceanic distribution. Common Arm Squids are typically mesopelagic or bathypelagic organisms, inhabiting the open ocean at considerable depths during the day and often migrating toward shallower waters at night to feed. Like other oceanic squids, they are likely important components of marine food webs, serving as both predators of small fish and invertebrates and as prey for larger marine predators such as cetaceans and seabirds. The Data Deficient listing underscores the need for additional research into the biology, population dynamics, and conservation requirements of this understudied species. Biological traits of this species remain poorly documented in the scientific literature.