Crown-of-thorns starfish lie in wait for corals to recover

It is common knowledge that the crown-of-thorns starfish is the bane of coral reef communities. What is lesser known is that this species does not feed on only corals. Rather, in its juvenile stage, it feeds on algae. Then, as it matures into an adult, it will switch to a diet of corals.

Researchers Dione Decker (left) and Professor Maria Byrne, with an adult crown-of-thorns starfish at the Great Barrier Reef.
Ecology & Science

It is common knowledge that the crown-of-thorns starfish is the bane of coral reef communities. What is lesser known is that this species does not feed on only corals. Rather, in its juvenile stage, it feeds on algae. Then, as it matures into an adult, it will switch to a diet of corals.

Based on new research reported in the Biology Letters journal, the starfish has the ability to adjust the timing of its dietary change based on the availability of coral in the vicinity.

X-RAY MAGAZINE FEATURE

Shark Fishing: Can Commercial Shark Fishing Be Sustainable?

With the loss of at least 90 percent of sharks worldwide, it would seem to be urgent to protect the ones that remain. Every global study of their status has reported a more dire situation than the last, and that the targeted hunt for the shark fin trade is responsible for their catastrophic depletion.

Words:
Ila France Porcher
Images:
Lemon sharks
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Ecology & Science

Only one-third of shark species are considered safe, and the most threatened are those accessible to fishing—those within about 1,000m of the surface, or, for seafloor dwellers, 3,000m in depth.

Shark fins are among the most expensive seafood products. The total declared value of the world trade in shark products is close to US$1 billion per year and it is associated with much illegal activity, including murder. To supply the trade, intense shark fishing spans all oceans.

X-RAY MAGAZINE FEATURE

Developing the Mindset of a Successful Image Maker

Is underwater photography difficult? Actually, no—at least, not to any significant degree when compared with any other discipline of photography. Each single stage of creating an underwater photograph, if seen in isolation from the rest, is not so tricky. It is the sum of all its parts, as well as mastering the whole, which can appear confusing at times. It is often believed that professional photographers have “special secrets,” which make their shots stand out from the rest, but mostly, it is rather a question of following a proper mindset.

Words:
Rico Besserdich
Images:
Rico Besserdich
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Photo & Video

In terms of underwater photography, we can say that the mindset is the systematic approach to staying organized and getting the best out of our photo dives. If you, for example, tend to run around your hotel room, searching for your housing’s o-ring in the last stressful minutes before the departure of the dive boat, while at the same time, wonder about whether or not you have charged your strobe batteries (and where are those batteries, by the way?), you could definitely use a change of mindset.

Mating Sharks and Tonic Immobility

Shark Tales, in X-Ray Mag's issue #63, focused on pain in fish and sharks, and included a short piece on mating behaviour. The violence of the encounter is typical of mating sharks, thus raising the question of the suffering of the female shark during mating.

mating wounds
Ecology & Science

So I asked leading shark ethologist and behaviourist, Professor Samuel 'doc' Gruber to elaborate. After pointing out how much pain women feel when they give birth, making the point that suffering has no effect on reproduction, he reminded me that sharks evolved their mating behaviours and the physical structures involved, separately from other animals.

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