No single feature unites all relic lineages, but there are some common strategies that help them to survive. Here's what you need to live a very long time....
LIVE ON THE EDGE
With fewer rival species, extreme habitats provide refuges for many relics:
- Cold Alpine environments are home to organisms such as ice crawlers and grigs.
- Deep oceans provide a safe haven for frilled sharks and vampire squids (one of the weirdest sea animals).
- Hot hydrothermal vents are inhabited by archaeabacteria.
PROTECT YOURSELF
Some relics have exceptionally effective defence mechanisms:
- Amoebocytes in horseshoe crabs blood create clots when exposed to bacterial toxin, protecting the internal organs from infection
- Scorpions have a beta-carboline coating their bodies that limits ultraviolet penetration
- Yews contain toxins that make them unpalatable to almost any herbivores.
3 HAVE A BACK-UP PLAN
Relics can often survive long periods of dormancy or major damage to their bodies:
- Lungfish spend months buried in the sand if water becomes unavailable.
- Cycads can spend many months without leaves and roots, and can survive almost complete burning.
- Tadpole shrimp eggs can live for years out of water, hatching and reproducing with amazing speed when rehydrated.
FORM ALLIANCES
Some relics have become more adaptable and competitive by developing partnerships:
- Cycads have a symbiotic relationship with cyanobacteria. These take nitrogen from the air, enabling the plants to grow in virtually sterile conditions.
- Termites have flourished since the Jurassic thanks in part to their symbiosis with protozoans, which help them to digest wood.
BE FLEXIBLE
Members of very old lineages can often live in a range of environmental conditions:
- Tardigrades (also known as water bears and one of the weirdest animals in the world) can withstand complete desiccation, very high pressure and temperatures ranging from -272°C to 150°.
- Ferns grow in both full sun and shade, thanks to their unique photoreceptors.
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Main image: Lungfish © Getty Images