THE ANIMAL FILES

Reindeer

Rangifer tarandus

Cold legs can help keep the body warm.

Reindeer manage heat along a long route from the body core to the feet and through the nose. Their hooves also change with the season. These adaptations connect circulation, breathing and contact with snow rather than depending on a thick coat alone.[1]

Follow the evidence ↓
Reindeer
Image: Dean Biggins (U.S. Fish and Wildlife Service) · Commons · Public domain
Recycling heat in the legs
Countercurrent exchange reduces heat loss.[1]
The nasal exchange
Nasal passages warm inhaled air.[1]
Seasonal foot contact
Winter pads expose more hoof rim.[1]

Recycling heat in the legs

Warm outgoing blood transfers heat to cooler blood returning towards the body. Less warmth reaches the exposed extremities and more returns inward. A cooler leg surface can therefore accompany conservation of core heat rather than indicating the whole animal is equally cold.[1]

The nasal exchange

Specialised nasal passages provide exchange surfaces for breathing. Incoming cold air is warmed, while moisture can condense from outgoing breath. This recovers some water that would otherwise leave with exhaled air and moistens the next incoming air.[1]

Seasonal foot contact

Summer footpads become softer on wet tundra. In winter they tighten, exposing hoof edges that engage crusted snow and ice. Hooves also dig through snow to reach food, so winter footing and winter feeding use the same structures.[1]

A COMMON MIX-UP

Must warm-blooded animals keep every body surface equally warm?

No. Reindeer conserve heat through controlled exchange, with cooler extremities helping reduce losses.[1]

TRY A LITTLE REASONING

How can a hoof help with both travel and obtaining winter food?

Reveal the explanation

Its edges improve contact with crusted surfaces, and digging opens access to food under snow.[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 — Reindeer (cited revision)
  2. NCBI Taxonomy — Rangifer tarandus

Last fact check:

One discovery leads to another

MooseA deer that browses below the waterline.Alces alces ↗Roe deerA field can be a feeding place while a hedge serves as refuge.Capreolus capreolus ↗White-tailed deerCounting antler points is not the same as counting birthdays.Odocoileus virginianus ↗