Beroe abyssicola, 4.7 inches long Aequorea victoria. Transparent and colorless most of the time, the crystal jelly can also light up like a firefly—to what end isn’t certain. The genes ...

The most commonly spotted were the huge barrel jellyfish - but rarer warm-water crystal jellyfish were also seen. The barrel, or “dustbin-lid”, jellyfish can grow to more than one meter in ...