Episode 194 – Aldabra Giant Tortoise: Elephants of the Atoll

“…and today we’re talking about the largest shelled reptile that lives on land maybe! But more on that later…”

A strange reptile that lives on a strange type of island will surely deliver in the weird department. Islanders are known for showing some interesting adaptations that mainlanders may find funny. But when you’re surrounded by the ocean, it pays to be unique and self-sufficient. The Aldabra Giant tortoise is a sizable, shelled, super-reptile large enough for a child to keep as a steed. But being large and in charge of your domain is one way  to make a path through Life, Death, and Taxonomy. 


  • He’s a giant tortoise
  • Has a massive, thick, brown shell made up of hexagonal plates that protect his squishy innards
    • While the outside is made of a hard keratin, the inside of the shell isn’t solid – rather it’s a honeycomb structure filled with air pockets to make the shell light for the tortoise to carry
  • It has short, scaly legs with stubby claws for digging and getting traction
  • Its neck is super long and can stretch to reach taller plants
  • I couldn’t find any info on whether they can retreat fully inside their shells but it doesn’t look like they can just looking at them and there’s no real reason for them to since they don’t have natural predators.

Measure Up

Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com. We don’t have a new Measure Up intro!

  1. Sulcata tortoise
  2. Sloth bear
  3. Barbados Raccoon
  4. Crested porcupine

Carapace Length

  • 122 cm (48 in)
  • How many Aldabra tortoises go into the length of the Aldabra atoll?
  • Hint: An atoll is an interesting island that’s formed by a coral reef that rises above the water. It’s a ring-shaped piece of land that partially or completely encloses a lagoon. Aldabra is a long oval shaped ring.
  • 27,852 tortoises. The atoll is 34 km (21.1 mi).


  • 250 kg (550 lb)
  • How many of the world’s shortest cows, Rani, go into an Aldabra tortoise?
  • Hint: The two-year-old Bhutanese cow made records after going viral in July of this year. The tiny short-rib was small due to genetic problems caused by inbreeding. She unfortunately passed away a few months later. 
  • 9.6 Ranis. Rani was 26 kg (57 lb). She was just 50.8 cm (20 inches) tall.

Fast Facts

  • Range: Aldabra Atoll in Seychelles, a tiny sovereign group of islands in the Indian Ocean northeast of Madagascar.
  • Diet: Herbivores that eat leaves, grasses, and plant stems. They also eat fruit in captivity.
  • Lifespan: up to 200 years – longest-lived vertebrates. The longest recorded lifespan is Adwaita 255 (1750-2006) – older than America. Currently, the oldest living tortoise is Jonathan at 189 years (born 1832).
  • Behavior:
    • Can book it at a blistering 0.3 mph
    • They can also swim since the air pockets in their shell allow them to float. It is thought that they can survive floating on the water for up to a month
    • They are the largest animals in their little island ecosystems and have no natural predators as adults, so they act as mini elephants – keeping shrubbery low and creating pathways for other animals to use.
  • You can buy an Aldabra tortoise for $1900 if you’re prepared to keep something the size of a Prius in your bedroom for 6 or 7 generations.

Major Fact: Elephants of the Atoll

Aldabra tortoises shape their environments in more ways than one. Despite the fact that they’re been seen eating birds, tortoises are primarily vegetarians. They enjoy grazing on fresh grasses and other plants that blanket their home islands. 

On the island of Aldabra, you may see a unique grass that grows short and close to the ground. What makes this grass unique is that it’s not just one grass species but several different species all bunched together. These plants are called tortoise turf, and it’s made up of more than 20 different grasses, weeds, and flowering plants. 

These grasses aren’t just naturally short and commingling plants, they’re adapted to life under the tyrannical rule of their reptilian overlords. Tortoise turf is adapted to be short. Their dwarfed size helps them to optimize for the tortoise’s close-cropping grazing style.

These plants also adapted to grow seeds closer to the ground rather than high up to avoid tortoise seed-chomping. The tortoises also eat other plants but tortoise grass makes up 61% of their diet.

But co-evolving isn’t the only way tortoises shape their environment. 

What do Aldabra tortoises and elephants have in common? They both work to create pathways through their environment. Tortoise grazing has these reptilian tanks traveling all over the island, stomping down plants and shrubs in their path. Like elephants, they’re even able to knock down trees. 

This is a simple but important role in environments with densely grown vegetation. Smaller animals are able to use these pathways to move around the island to access resources. 

You wouldn’t think tortoises would be very good at plant pulverizing. But there’s a video of a tortoise keeper complaining about a tortoise that keeps knocking down a wooden fence.  

Ending: So stretch your freakishly long neck, eat your salads, and remember that slow and steady wins the longevity race like the Aldabra giant tortoise here in Life, Death, and Taxonomy.