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Do Dead Turtles Float?

Have you ever wondered what happens to sea turtles after they die? Where do their bodies go, and do they float on the ocean’s surface or sink to the seafloor? As sad as it is to think about, the death of a sea turtle is a fascinating scientific process. Read on to learn some surprising facts about the fate of deceased turtles!

Do Dead Turtles Float?

Do dead turtles float?

When a sea turtle dies, its body doesn’t necessarily float on top of the ocean. So, do dead turtles float or sink? Well, it depends. When a turtle first dies, gasses start building up inside their bodies through decomposition. 

This causes fresh carcasses to float at the surface initially. Research has found that loggerhead turtle carcasses usually float for 2-3 days before sinking. But what makes them eventually sink? 

The carcass becomes less buoyant and heavier as the gasses escape the body. Things like temperature, scavengers, and ocean currents also speed up the sinking process. 

Some key factors impact whether a dead sea turtle floats or sinks:

  • Size – Larger turtles float longer than smaller juvenile turtles. Adult turtle carcasses can float around for up to 7 days.
  • Decomposition – Gases filling the body make it float initially, but escaping gases cause sinking. Faster decay means faster sinking.
  • Predation – Scavengers speed up decay and tear apart the buoyant carcass, causing it to lose buoyancy and sink more quickly. 
  • Trauma – Major trauma like boat strikes causes turtles to sink immediately as gases can’t fill the damaged carcass.
  • Water Conditions – Colder water temperatures slow decomposition, allowing more time to float. Warm waters in the tropics speed up sinking.

Most dead turtles end up sinking to the bottom within about one week. Their rotting bodies are too dense to keep floating for long. However, the exact time a carcass remains at the surface depends on environmental conditions and the turtle’s intactness.

Do Turtle Shells Decompose? 

So, a dead sea turtle’s flesh will eventually disintegrate and fall away as the carcass rots. But what about their tough outer shells? Do turtle shells also decompose after death?

Because turtle shells are made of keratin – the same protein that makes up hair and fingernails – they are very durable and resistant to decomposition. However, over time, the shells will break down through natural processes:

  • Scavengers – Small marine scavengers like crabs will gradually nibble away and break apart portions of the shell as they eat turtle remains. This speeds up shell breakdown.
  • Bacteria – As with most organic matter, bacteria digest and decompose the shell over time. The keratin becomes more brittle from bacterial activity.
  • Wave Action – Tumbling around the ocean bottom batters shells against rocks and sand, abrading their outer layers. This also splits and weakens the shell.
  • Chemical Reactions – Exposure to hydrogen sulphide and low oxygen environments in sediment chemically alters and weakens the shell. Acidic seawater also degrades the calcium carbonate components.

Turtle shells can survive intact for years before fully decomposing. In one case, a well-preserved turtle shell washed up on a beach that was determined to be over 1000 years old! 

Most likely, only the outermost layer remained, with the inner shell long gone. So, while shells do eventually break down, their decomposition is very slow. All those fragments of old turtle shells you find washed up? They’re likely decades or centuries old. 

What Eats Dead Sea Turtles?

Now that you know dead turtles will spend some time floating at the surface but ultimately sink, you may wonder what happens to their remains at the bottom of the ocean. 

Do they pile up down there? Many marine scavengers have evolved to take advantage of sunken turtle carcasses! Here are some of the deep sea creatures that you can thank for recycling decomposing sea turtles:

  • Small hagfish and sleeper sharks will feed on recently fallen carcasses. They tear away soft flesh.
  • Giant isopods, spider crabs, and amphipods swarm the shell, eating meat and fat scraps. Their nibbling also destroys the shell over time. 
  • Worms, starfish, and octopods help break down leftover tissue and internal organs.
  • Larger sharks, like tiger sharks, may scavenge the skeleton if meat remains. Their powerful jaws can crush bone.
  • “Zombie worms” bore into bones to ingest nutrients and feed on decomposing tissues. 
  • Bacteria decompose remaining tissues and break down keratin in the shell.  
  • Other invertebrates, like molluscs and sponges, absorb dissolved organic matter from the remains.

So, in the abyssal zone where dead sea turtles settle to the seafloor, scavengers make quick work of their carcasses. These efficient zombie-like eaters recycle the turtle remains to nourish other deep-sea life, so not much goes to waste!