Interesting Facts About the Blue Shark

The blue shark (Prionace glauca) is a slender, deep-blue requiem shark found in every temperate and tropical ocean on Earth. It is one of the most wide-ranging sharks alive, famous for basin-crossing migrations, long wing-like pectoral fins, and distinctive curved, serrated teeth. 

Known for its striking cobalt colouring and graceful movement, the blue shark fascinates divers, scientists and ocean lovers alike. Below are the facts that matter most — including how to recognise a real blue shark tooth before you buy one.

Blue shark quick facts

1. One of the ocean's great long-distance travellers

Blue sharks are true wanderers. Tagging studies have documented individuals crossing entire ocean basins — transatlantic journeys of several thousand kilometres are well recorded, and some tracks exceed 9,000 km. They follow seasonal currents and temperature fronts to stay with their prey, and they perform daily vertical migrations too: deeper by day, shallower by night. This nomadic, open-ocean (pelagic) lifestyle is exactly why the species is spread across so much of the planet.

2. Built for efficient, elegant swimming

With a long, tapered body and unusually long, narrow pectoral fins, the blue shark is shaped for economical gliding over vast distances rather than short bursts of speed. Those wing-like fins are one of the easiest field marks for identifying the species. Divers often call blue sharks "the ballerinas of the shark world" because of their smooth, flowing, almost weightless movement.

3. The blue that gives it its name

Few sharks are as instantly recognisable. The blue shark has a deep indigo back that fades to bright blue on the flanks and a crisp white belly. This pattern, called countershading, is beautiful but also functional: seen from above the dark back blends with the deep water, and seen from below the white belly disappears against the bright surface. The colour is most vivid in living adults and fades quickly after death, which is one reason live encounters are so memorable.

4. Blue shark teeth: how to identify the real thing

Blue shark teeth are one of the most collectable in the trade, and knowing what a genuine one looks like protects you from imitations. The species shows what biologists call heterodonty — the upper and lower jaw teeth are different shapes:

• Upper teeth: broadly triangular with a distinctly curved (recurved) cusp, finely serrated edges, and bases that overlap like roof tiles. Roughly 14 per side.
• Lower teeth: narrower, straighter and more upright, with finer serrations. Roughly 13–15 per side.

That combination — a curved, serrated, triangular upper tooth with overlapping bases — is the signature of a real Prionace glauca tooth, and it is what makes each one ideal for grabbing slippery squid. It is also what makes them such a distinctive keepsake when turned into jewellery.

Ethically sourced blue shark teeth are often set into pieces like this real blue shark tooth necklace. Across many cultures, wearing a shark tooth necklace has long symbolised protection, courage and a connection to the sea.

5. Social by nature, but still a predator

Unlike many solitary sharks, blue sharks are frequently seen in loose aggregations, often sorted by size and sex — a pattern scientists describe as fission-fusion sociality, where individuals join and leave groups around food and mating opportunities. They remain capable hunters, working slippery schools of squid and fish with quick, agile turns.

Are blue shark teeth legal and ethical to buy?

Yes, when they are sourced and documented correctly. The blue shark is listed under CITES Appendix II, which means international trade is legal but regulated: it requires permits and non-detriment findings to ensure trade doesn't threaten wild populations. Responsible sellers work only with fishery by-products (teeth recovered from sharks already caught in legal, managed fisheries) rather than sharks taken for their teeth.

This is an important distinction. Some species, such as the Great White, are protected far more strictly and cannot be sold at all in places like South Australia. Blue shark teeth, by contrast, can be traded legally and ethically with the right certification - which is exactly why they are one of the most responsible choices for genuine shark tooth jewellery.

Frequently asked questions about blue sharks

What do blue shark teeth look like?

Upper teeth are triangular with a curved cusp, fine serrations and overlapping bases; lower teeth are narrower, straighter and more finely serrated. The curved, serrated upper tooth is the easiest way to identify a genuine blue shark tooth.

Are blue sharks endangered?

The blue shark is currently listed as Near Threatened on the IUCN Red List (assessed 2018) and is protected under CITES Appendix II. It is heavily affected by longline bycatch and the fin trade, which is why regulated, by-product sourcing matters.

How big do blue sharks get?

Adults are typically 1.8–2.5 m long, with the largest reliably recorded individuals reaching around 3.8 m and up to roughly 206 kg.

What do blue sharks eat?

Their diet is dominated by squid and small schooling fish, which their gripping-and-cutting teeth are perfectly adapted to catch.

Where do blue sharks live?

They live in the open ocean across every temperate and tropical sea, including the Mediterranean, ranging from roughly 60°N to 50°S.

Is it legal to own a Blue shark tooth?

In most countries, yes, provided the tooth comes from a legally traded, CITES-compliant source. Reputable sellers supply teeth as documented fishery by-products.

A piece of the ocean, sourced responsibly

The blue shark is more than a beautiful animal - it is a keystone of open-ocean ecosystems and a reminder of how far life travels beneath the surface. If its strength and grace speak to you, a responsibly sourced real shark tooth necklace is a meaningful way to carry a piece of that power with you. Just make sure any shark tooth jewellery you buy comes from ethical, legal and certified sources - so these remarkable sharks remain part of our oceans for generations to come.