The same Haddon’s anemone, bleached, Emily Bay, Norfolk Island, 10 March 2024
This is a Haddon’s sea anemone – also known as a saddle or carpet anemone (Stichodactyla haddoni). Haddon's anemones are covered in a dense ‘carpet’ of sticky, stinging tentacles that they use to catch passing fish and shrimps. We only have a couple inside the lagoon, and this one has set up home right in the middle of Emily Bay, where it’s spent years shrugging off drifting sand and the occasional nibble from a hungry wrasse.
Haddon’s anemones can grow very large – up to 80 cm across – though most reach around 40 to 50 cm when fully expanded. This one is hiding in plain sight, rarely noticed by swimmers and snorkellers eager to reach the reef. It sits in about three metres of water, give or take, often with one or two yellowstriped goatfish (Mulloidichthys flavolineatus) hanging about. He’s a little bit beige, a lot persistent – definitely a stayer.
I first photographed this anemone back in February 2020 with my brand-new underwater camera, though that first photo is pretty dreadful and not worth sharing. The next attempt, in April, wasn’t much better – it had a sickly green tinge while I was still learning my settings. Since then, I’ve photographed Haddon whenever the thought has struck me, just out of curiosity to see how he’s doing.
Haddon's anemones are covered in a dense ‘carpet’ of sticky, stinging tentacles. This is a close-up of the other known specimen of this species inside the lagoons, Norfolk Island
No one really knows how long these anemones live, but a hundred years is probably a fair guess for a wild one like this. In other regions, they often host clownfish, but Norfolk’s own McCulloch’s clownfish (Amphiprion mccullochi) – the rare, dark-bodied species found only here and at Lord Howe Island – doesn’t seem to visit the lagoon.
Like corals, sea anemones host microscopic algae called zooxanthellae – affectionately known as ‘zoots’. The zoots photosynthesise and provide up to 90 per cent of the anemone’s food. In return, they get a safe home inside the anemone’s tissues. It’s a mutually beneficial relationship, but when the water gets too warm or conditions stressful, the anemone expels its zoots, losing its colour and effectively bleaching. Once conditions improve, the zoots move back in and the colour returns.
If you look at the photos below, you’ll see how this plays out. Between February and May, if the water gets too uncomfortably warm, Haddon tends to pale noticeably before slowly regaining his colour.
This spring, though, something seems different. Haddon is already looking bleached – and it’s only early October. Was he like this in late August or September as well? Sadly, I missed photographing him then, so I can’t be sure.
Because the photos aren’t taken at regular intervals, it’s hard to say exactly what’s stressing him, but we know that sea anemones are sensitive not just to heat but also to changes in salinity. Sudden influxes of freshwater can cause them to expel their zoots and bleach too. Since April 2025, when the long drought finally broke, Norfolk has had a run of heavy rain – one of the wettest winters on record. Could that sudden shift from salty to diluted water have triggered this early bleaching?
There are plenty of questions and not many answers. What we do know is that Haddon’s colour tells a clear story of stress and recovery – bleaching during hot or unsettled times, then slowly bouncing back. He’s been doing this quietly for years, a beige barometer of lagoon health right in the middle of Emily Bay.
Rainfall for Norfolk Island, 2025