Reddish-brown with a distinctive fan-shaped pattern on its back, this crab is the archetype of what most people imagine when they think of a crab. The name Cancer comes from Latin, and it fits. Hard shell, powerful claws, sideways scuttling gait – everything about it says "crab" in the most fundamental sense. The edges of the carapace are toothed. This gives it a rugged, armoured appearance. Form follows function. Under rocks and in crevices, daylight hours are spent in hiding. The cancer crab hides from predators. Larger fish, octopus, and seals patrol the reef during the day. It wedges itself into gaps so tight that extracting it without breaking the shell is nearly impossible. This is not cowardice. It is arithmetic. A hidden crab lives to see another tide. A crab in the open becomes someone else's lunch. Survival favours the concealed. Night and high tide bring it out to feed. The cancer crab emerges from its hiding place. It begins to scavenge across the reef and sand flats. It eats dead fish, small molluscs, and anything else organic that it can crush with its claws. The claws are not symmetrical. One is larger and used for crushing shells. The smaller claw handles cutting and manipulating food. When a mussel or small snail is found, the crusher claw cracks the shell. The smaller claw picks out the soft flesh. Efficiency is key. Waste is minimal. Moulting is the most dangerous part of its life. The crab absorbs water and swells. It cracks the old exoskeleton along predetermined lines. It backs out, leaving behind a perfect, empty replica of itself. The new shell is soft and flexible. The crab is vulnerable to predators during this time. It hides in a crevice for several days. It absorbs calcium from the water and from the old shell, which it often eats. Only when the new shell hardens does it emerge again. Vulnerability is temporary. Protection returns. Recreational fishers sometimes collect cancer crabs for bait or for eating. The meat is sweet and delicate, but there is not much of it. The crab is also caught as bycatch in rock lobster pots and set nets. It is not targeted commercially. No formal stock assessment exists. Populations appear stable across most of its range. Stability is relative. Pressure is constant. Climate change may alter this stability. Warming waters affect the distribution of prey. Coastal development destroys the rocky reef habitat it depends on. The cancer crab is adaptable, but it has limits. For now, it remains a common sight in rocky harbours. It scuttles away when disturbed. It pinches when provoked. It does what crabs have done for millions of years. Persistence is its strategy. Adaptation is its tool. A final warning: its claws can deliver a painful pinch. Not dangerous, but memorable. Fingers inserted into crevices without looking tend to regret the decision. The cancer crab does not seek out conflict. But it does not retreat from it either. Respect the claw, and the claw will respect you. Caution is wise. Pain is a teacher.