Nile crocodiles in Tanzania — living dinosaurs in the water

An animal from before the dinosaurs

The Nile crocodile is one of the oldest surviving animal species on earth. They have existed for 200 million years — they lived alongside the dinosaurs and survived them. They have barely changed since, because evolution had little reason to improve them.

In Tanzania they live in virtually every river and lake. But in two places they are notorious: the Grumeti River (in the western Serengeti) and the Mara River (at the Kenyan border).

The waiting strategy

The crocodile is the most patient hunter in Africa. For months they lie almost motionless on the banks or just below the water surface. They barely eat — their metabolism is so slow they can go months without food.

Then: the migration approaches.

The crocodiles know it. They feel the vibrations in the water. They smell the approaching animals. They gather at the river crossing points — sometimes dozens or hundreds at once.

And then they wait.

The crossing: a bloody but essential scene

The wildebeest herd stands at the bank of the Grumeti or the Mara. Sometimes for hours — the animals are afraid, they sense the danger. But the urge towards grass on the other side is stronger.

Then one wildebeest jumps. Thousands follow.

The crocodiles strike. They use their tails to surround wildebeest, their jaws to bite and pull under. An adult crocodile can hold a 250 kg wildebeest in its jaws and rotate — the "death roll" — to tear off chunks of flesh.

It is rough. It is bloody. And it is one of the most essential moments in the ecosystem.

Facts that surprise most people

- A Nile crocodile reaches 5 to 6 metres long in Tanzania (the largest) - They bite with 5,000 Newtons — the strongest bite of any living animal - They can almost stop their heart to remain underwater without breathing for up to an hour - Crocodile temperature determines sex: warm nests = male, cool nests = female - They are social animals — on the bank they lie next to each other without conflict; in the water they are rivals

Mother crocodiles: the unexpected story

Very few people know this: female crocodiles are excellent mothers.

They dig nests in the bank, guard the eggs for 3 months, and carry the newly hatched crocodiles (10–15 cm long) in their mouth to the water. They guard them for weeks.

It sounds improbable — but I have seen it with my own eyes.

Where to see crocodiles safely

**Grumeti River (western Serengeti)** — the first river crossing of the migration. In May–June enormous crocodiles are present here. Some are so old and large they barely move — but are deadly quick when they need to be.

**Mara River (northern Serengeti)** — the most famous crossing point. July–September. Here are the largest crocodile concentrations during the migration.

**Lake Manyara** — crocodiles at the lake shores. They are less spectacular than at the rivers, but visible at closer range.

**Selous/Nyerere National Park** — the Rufiji River has one of the largest crocodile populations in Africa. Boat trips here are a separate experience.

Safety

Crocodiles in the water are always more dangerous than they appear. They lie still, sometimes with only their eyes above the surface. They can move incredibly quickly over short distances.

Rule: never stand at the waterline. Keep at least 5 metres from the bank of any river or lake.

From a safari vehicle you are completely safe. Crocodiles are water-focused — they rarely come far onto land.

The grandeur of age

What moves me most about crocodiles is not their strength or their teeth. It is their age.

When I look at a large crocodile on the Grumeti bank — resting in the sun, motionless, its eyes half-closed — I think: this animal is perhaps 80 years old. It has witnessed hundreds of migrations. It has seen Tanzania change.

And it is still waiting. Exactly as its ancestors waited 200 million years ago.

That is something to respect.