Species deep dive · Selachimorpha

Shark size and weight: four hundred million years of getting it right

Sharks were old when the first trees grew. Today they range from twenty-centimetre lantern sharks to the twelve-metre whale shark — and a handful of their most charismatic representatives patrol the great lagoon of the Oceanographic Museum of Monaco.

Sizes across the shark world

Blacktip reef shark ≈ 1.6 m · 20 kg The swift, black-finned patrol of the museum’s tropical lagoon

Nurse shark ≈ 3 m · 150 kg A slow, bottom-resting giant with the temperament of a sofa

Blue shark ≈ 3 m · 60 – 200 kg The Mediterranean’s own open-ocean traveller, deep indigo above

Scalloped hammerhead ≈ 4 m · 150 kg The wide head is a living metal detector, packed with electroreceptors

Great white shark 4.5 – 6 m · 1 – 2 t Rare but real in the Mediterranean, which has its own small population

Whale shark 10 – 12 m · 15 t + The largest fish on Earth — a filter feeder harmless to anything bigger than plankton

Lifespan 30 – 70 + years Greenland sharks may live four centuries; most large sharks mature after age 15

Teeth replaced in a lifetime 10 000 + A conveyor belt of teeth moves forward through the jaw and is never turned off

A skeleton of cartilage, a battery of senses

Sharks solved the problem of being a large predator without a single bone. Their skeletons are cartilage — half the weight of bone, reinforced with mineral tiles where strength is needed. Lighter frames let big sharks swim efficiently, and most must swim: with no swim bladder, many species stay afloat only through forward motion and a vast, oil-rich liver that acts as an internal float.

What truly sets sharks apart is their instrumentation. Smell is legendary but often exaggerated; the real marvels are subtler. The lateral line feels pressure waves from struggling prey. The ampullae of Lorenzini — gel-filled pores around the snout — detect the faint electric fields of heartbeats and muscle contractions, letting a shark find a fish buried in sand in total darkness. Some species see better in dim water than a cat. A great white cruising the depths is not swimming through emptiness; it is reading a rich, flickering map of everything alive around it.

Their vulnerability is arithmetic. Large sharks grow slowly, mature late, and produce few young — a sand tiger shark may carry two pups for a year. A population cannot withstand losing a quarter of its adults each year, yet that is roughly what industrial fishing has taken. The IUCN now classifies around a third of shark and ray species as threatened with extinction, and the Mediterranean — fished intensively for two thousand years — has lost most of its large sharks. Every shark in a public aquarium is, among other things, an ambassador for cousins who no longer exist.

The sharks of the Rock

In the museum’s 450,000-litre lagoon, blacktip reef sharks and nurse sharks cruise within a metre of the glass — close enough to watch the gill slits work and the eye track your movement. Monaco’s engagement with sharks goes further than display: the principality backed international protections for several shark species, the Oceanographic Institute campaigns against shark finning, and the museum participates in European husbandry and research programmes that study how sharks live, grow and breed in human care. Jacques-Yves Cousteau, the museum’s director for three decades, spent much of his career correcting the record on sharks — pointing out that the animal we invented in films barely resembles the one in the sea.

Sharks: quick answers

What is the biggest shark?

The whale shark, commonly 10–12 metres and over 15 tonnes. The biggest predatory shark is the great white, at up to about 6 metres and 2 tonnes.

Are there sharks in the Mediterranean?

Yes — around 50 species, including blue sharks, hammerheads and a small great white population. Most are now rare after decades of intensive fishing.

Which sharks can you see in Monaco?

The Oceanographic Museum’s great lagoon is home to blacktip reef sharks and nurse sharks, alongside sea turtles and rays.

Are sharks dangerous to humans?

Worldwide, sharks bite a handful of people a year — fewer than are injured by vending machines. Most species, including all the Mediterranean’s common ones, avoid people entirely.