captive anemone

I’ve been reading The Ocean at Home: an Illustrated History of the Aquarium by Brend Brunner. It was a gift from Marcia Tanner back in 2006, and I’m just getting around to reading it, but it’s perfect timing.

Anthopleura xanthogrammica

Like nearly all texts about science history, there’s an undercurrent of the macabre. On page 26 there’s a story about Scottish scientist Sir John Dalyell who, in 1827, brought a captive anemone (Actinia equina) home from North Berwick and essentially kept it as an experimental pet in his home aquarium. He fed it “pieces of mussels and oysters,” so these must have been dead already, and he changed the water in the aquarium daily, supposedly.

D’Arcy Wentworth Thompson (On Growth and Form) wrote about this anemone in his book Science and the Classics. Apparently, this anemone outlived Dalyell by a couple of decades, passing away in 1887 at the age of sixty.

Sixty? I’m not sure what this means compared to life in the wild. Most sources on the net repeat this figure of sixty years as a general life expectancy for anemones with no explanation. Some of these same sites say  that anemones could theoretically live “indefinitely”, but that they don’t, as they usually fall victim to predators. However, because their cells don’t age, they’re impossible to date. Some small anemones from New Zealand are estimated to be over 300 years old. Here’s an interesting blurb:

“Recently, Joyce Wilkerson took a survey on captive anemone life span. Only 5 percent of hobbyists with 2-5 years of experience had been able to keep anemones alive for more than two years, and only 1 out of 32 anemones lived for more than 5 years. The anemones simply aren’t surviving.

When an anemone dies in an aquarium, it releases massive quantities of toxins that could decimate every animal you have in that aquarium. These anemones are fundamentally unsuited to aquariums.

Despite this, thousands of anemones are raided from the ocean. This is a tragedy, because in the wild, anemones can live for hundreds of years. They also reproduce very slowly. When an anemone with a 60 or 70 years ahead of it is taken from the ocean and left to die in an aquarium in just several months, it is a tragedy.

When an anemone is not given the chance to produce offspring, it is a tragedy. If we keep up these destructive collecting practices, there will be no anemones left in the ocean. They simply do not reproduce quickly enough to keep up with the demand of the pet trade.”

So… did Dalyell’s anemone live a longer life than it would have in the wild, similar to cats and dogs that live in domestic captivity? Or did it die decades or perhaps hundreds of years earlier than it should have in a predator-free environment? And if the latter is the case, was it due to loneliness, pining for the pulse of the tides or for the rush of the kill? No matter, the fact that there’s a thriving trade in anemones as pets is horrific, given the survival rates cited in Wilkerson’s survey. I understand the fascination with these miniature worlds. I used to build terrariums as a kid. But I definitely killed a lot of moss. I wonder if  we’ll ever outgrow this obsession for building miniature worlds – terrariums, aquariums, vivariums – given that they all, by definition, must end in miniature ecocides. And if these small worlds are a fad that’s now two hundred years old among a population that’s 7 billion large, these miniature ecocides must be adding up.