Sea Otter
The sea otter weighs 70 pounds, eats sea urchins all day, and represents 0.1% of kelp forest ecosystem biomass.
The sea otter weighs 70 pounds, eats sea urchins all day, and represents 0.1% of kelp forest ecosystem biomass. It should be a footnote. Instead, it's the linchpin - and discovering this cost us a century.
When otters were hunted to near-extinction in the 19th century for fur, we ran an unintentional experiment in network collapse. Within years, urchin populations exploded. Kelp forests that had stood for millennia were grazed to barren rock. Fish disappeared. Harbor seals declined. Bald eagles left. Dozens of species that never encountered an otter vanished because the kelp - their habitat, not food source - was gone. When biologists reintroduced otters in the 1960s-70s, kelp forests recovered within 3-5 years. One species restored, entire ecosystem rebuilt.
This is what keystone species means: some network nodes can't be replaced, bypassed, or distributed. The otter isn't just controlling urchins - it's maintaining the architecture that hundreds of other species depend on. Remove it and the system doesn't decline proportionally; it flips to an alternative stable state that resists reversal. Your business has keystones too: that engineer who understands the legacy system, that client whose logo attracts others, that API that fifteen integrations depend on. They look like 0.1% of headcount or revenue. Lose them and you discover they were 100% of structural integrity.
Notable Traits of Sea Otter
- Keystone predator controlling sea urchin populations
- Enable kelp forest stable state
- Demonstrate threshold effects in ecosystem transitions
- Keystone predator
- Controls urchin populations
- Enables kelp forest ecosystems
- Near-extinction and recovery demonstrates keystone effects
- Keystone species
- Sea urchin predator
- Kelp forest ecosystem engineer
- Controls sea urchin populations
Sea Otter Appears in 4 Chapters
Sea otters control sea urchin populations, determining whether ecosystems exist as kelp forests or urchin barrens. Reintroducing otters can shift systems between alternative stable states by pushing urchins below critical thresholds.
Alternative Stable States →The canonical keystone species example. When hunted to near-extinction, urchins exploded and kelp forests collapsed. Reintroduced in the 1960s-70s, kelp recovered within 3-5 years. Less than 0.1% of ecosystem biomass, restructures the entire system.
The Canonical Keystone →Sea otters demonstrate that impacts can far exceed biomass through network position. Their removal causes kelp forest devastation, eliminating habitat for dozens of species - showing the limits of modular trophic thinking.
Network Position Matters →Mentioned alongside wolves and beavers as keystone species whose disproportionate ecosystem effects cannot be compensated for by other species - illustrating the limits of ecological redundancy.
Limits of Redundancy →