by Tina Kelly, Shaw Centre for the Salish Sea –
Imagine visiting the Shaw Centre for the Salish Sea, only to find a room of empty exhibits. Hard to fathom if you’ve ever been mesmerized by the jellies in our Drifter’s Gallery but this is exactly what would happen if we didn’t grow our own jellies.
Jellyfish, including moon jellies – Aurelia aurita – have a wonderfully unusual lifecycle. The medusa – the most recognized phase of the lifecycle – blooms during summer months. If we relied on collecting wild jellies, for the better part of the year we’d be jelly-less. The remainder of the lifecycle is rarely encountered by the novice eye, in part due to their diminutive size.
Our Centre was designed to maximize the space accessible to visitors. Lucky for us only a small fraction of our 10,000-square-foot footprint is required for the jellyfish nursery. Aside from the specially designed tanks – or kreisels – all we need is a mini bar fridge, a few Mason jars, some plastic containers, a shallow Pyrex dish, a turkey baster and a small trough with circulating sea water.
Along with proper equipment and hardware, staff care and diligence keep the jellies drifting. Rearing healthy jellies requires excellent water quality and although sea water enters the aquarium directly from the Salish Sea at a rate of 55 gallons per minute and flows through a series of filters, the centre’s team of aquarists closely monitors all of the important parameters – temperature, salinity and water flow.
Our Aquarists must also magically alter the seasons with the help of the mini bar fridge. The small, sessile polyp phase of the cycle takes place over winter. Polyps are placed in the fridge – suspending them in “winter” – for as long as needed. In the wild, increases in the spring water temperature cue each polyp to reproduce asexually, creating many genetically identical clones or ephyra. By removing polyps from the fridge and placing them in moderately warmer water, asexual reproduction is initiated and we are provided with the ephyra stage.
Ephyra are tucked away behind the scenes, drifting about in Mason jars until they develop into adults or medusas, and are big enough to go on display. Every 48 hours, our Aquarists’ fine motor skills are tested by carefully sucking up the tiny ephyra, one by one, with a turkey baster in order to refresh the jar water. It’s finicky work but worth the reward: jellies on display!
Though we may not be able to see the difference, each medusa is a boy or a girl. Having two sexes allows for sexual reproduction and consequently provides for genetic differences in offspring. Medusas broadcast, or release, eggs or sperm into the water around them. If the eggs are fertilized, larvae are created, they settle on a surface, become polyps and the cycle starts all over again.
It seems like a complicated lifecycle for an animal with no bones, blood or brain but we’ve mastered the skills needed to keep them circulating and to keep you captivated. On your next visit, observe our smack of moon jellies, look for different age cohorts and reflect on all of the care and detail needed to create the display.
The Shaw Centre for the Salish Sea opens at 10 a.m. daily.