The ocean is such a vast wilderness, and the beach brings you as close as you can get to it without getting wet.  Both you and your dog enjoy walking along the beach face, where the sand is somewhat hard from the water underneath, but your shoes keep your feet dry.  Today your dog is particularly energetic, and you think it will be good to let it run off the leash.  Nobody seems to mind if a dog comes up to investigate, and there don't appear to be signs that dogs have to be tethered.  Besides, what kind of trouble can a dog get into on a wide expanse of sand and surf?

All is going well, and your mind starts wandering to the various books waiting for you at home when you return from your walk, when your dog yelps in surprise and lunges forward.  You jolt back to the present moment and see a boat beached nearby, and wonder if that is what excited your pet.  It takes a few seconds to spot what your dog has identified: a cat sleeping on the deck.  Oh no!  Your dog hates cats.  This one seems more like a sitting duck, with no place to go.  You doubt that it can swim, or if it can, that it would dive into the ocean.  Drat it!  You should have used the leash after all.  The last thing you need is an angry cat owner and an injured pet on your hands.  Think of the liability!

Just as it seems that your dog is completely out of control, ignoring your frantic calls, the beach comes to life.  Out of the hinterland and sprinting across the backshore come the most amazing creatures you have ever seen.  They look like agave plants, but they have legs and arms, and are heading directly for your dog.  One of them reaches out its spiny arms and grabs your dog by the tail, and puts two more arms -- yes, two more arms -- around its body.  Then you feel the piercing pain of two spines in your own leg.  In the struggle you glance over at the boat and see several more agave creatures guarding the boat, while the cat looks nervously around for an avenue of escape.

It is all over before long, though.  Your dog cries out in pain as the spines on the agave creature dig into its flesh, and suddenly all the fire has gone from your pet's attack.  You breathe a sigh of relief, and then hear a strange sound coming from above, like the raspberry tart of a contemptuous onlooker.  Have you been observed?  You look around quickly, up onto the headland overlooking the beach, but there is nobody.  In a panic you scan the horizon and then lift your vision to the sky, where the fantastic vision of a floating palm frond, lips parted, tongue protruding, is mocking you and your pet.

Clearly, the beach has its own rules and enforcers, as well as overlords that protect those who belong to the sea.  You are just a visitor here, and you better mind your manners.  Heading for home, books forgotten and limping slightly, you hope your dog learned its lesson, but somehow you have your doubts.