THE ANIMAL FILES

Green iguana

Iguana iguana

Living in trees does not rule out a swim.

Green iguanas climb trees, are active by day and swim with powerful tail strokes. A light-sensitive parietal eye sits on top of the head, while leaves, shoots, flowers and fruit make up most of the diet.[1]

Follow the evidence ↓
Green iguana
Image: Rjcastillo · Commons · CC BY-SA 3.0
Activity
Mainly diurnal and often arboreal[1]
Swimming
Powerful tail strokes provide propulsion[1]
Main food
Leaves, shoots, flowers and fruit[1]

A light detector above the eyes

The parietal eye on top of the head detects changes between light and dark but does not form ordinary detailed images. Its sensory role is therefore different from the two large eyes facing the surroundings.[1]

A tail becomes a propeller

When swimming, the iguana holds its limbs near its sides and moves with strong tail strokes. Nearby water can also provide an escape route from its climbing habitat.[1]

Signals in the head and throat

Head bobs and the dewlap are used during social interactions and defensive displays. Posture and repetition contribute to the signal.[1]

A COMMON MIX-UP

Does a “third eye” give three complete views?

No. The parietal organ detects changes in light rather than forming a normal detailed image. Names do not guarantee identical functions.[1]

TRY A LITTLE REASONING

Why might a tree-dwelling lizard keep useful swimming abilities?

Reveal the explanation

Nearby water can provide an escape route from a climbing habitat. Swimming allows the iguana to use that route after leaving a tree.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Iguana iguana (adapted and translated; exact revision)
  2. NCBI Taxonomy — Iguana iguana (identity and game lineage)

Last fact check:

One discovery leads to another

Marine iguanaA seaweed meal ends with time in the sun.Amblyrhynchus cristatus ↗Common chameleonA chameleon’s changing colour is also a signal, not a background-copying machine.Chamaeleo chamaeleon ↗Gila monsterBeaded skin, a searching tongue and a fat-storing tail.Heloderma suspectum ↗