Captain Chumway won't have a pet aboard his ship. Far as he's concerned, a ship contains exactly four kinds of living thing — passengers, crew, vermin and food.

Of course, when the ship docks regularly at over six dozen planets, some of which have more than one kind of alien living there, sometimes they don't sort out so easy.

So when Gaspar "Last Gasp" Pimlico brought a dizzard aboard and named it Spud, he needed the best advice he could get on how to handle the situation. And who gives the best advice on the ship? Me — Rick Ramrod, special assistant to the captain.

The most sensible thing I could tell him was, "Don't."

Of course, I knew what was coming next. I had to stop myself from mouthing "But I already did" along with him.

So I told Gaspar the second most sensible thing: "Chuck him into recyke. Dizzards stink, shed, and excrete stuff us humans shouldn't even think about. Who'd be dumb enough want one for a pet?"

"Me," the Gasper admitted.

"Hmm. Lemme think for a minute."

I made him wait for it, but I'd known the answer all along.

I drawled a nice, slow, "Uh . . ." just so I could watch him perk up hopefully, before suggesting, "Maybe you could say you're raising it for food."

"But you can't eat a dizzard."

"Sure you can. It just takes a long time and you need real strong jaws." To keep from cracking up, I licked my lips. "Lots of trouble, but worth it, Gasp — definitely worth it."

Truth is, I'd just as soon eat a cigar roach as a dizzard. Or maybe I could feed the dizzard to the cigar roaches — it might make them go away.

Cigar roaches, by the way, are alien bugoids that got loose in the ship so long ago, nobody alive can remember when they weren't here. They survive by listening to brain waves. You can't poison 'em because they know where you left the poison, you can't trap 'em because they know where you left the traps, and you can't stomp 'em because they know where your foot's coming down. They're the second most disgusting things I know of — right after dizzards.

Anyway, the official reason Spud got fed was because Last Gasp was fattening him up to eat. Hey, I know, and you know, you don't give names to food. But I figured the captain was thick enough to let it pass, and I was right.

One day, I happened to be walking in the corridor, and the captain, a couple steps ahead of me, turned a corner and saw Gaspar and Spud playing "fetch". The captain gave Gasp a questioning look.

"Exercise, Sir," Gaspar told him. "It's exercise that'll firm him up." He paused a moment, saw me roll my eyes, then added, "Yum yum."

Exercise? Puh-leeze! The only exercise the dizzard got playing "fetch" was in the neck muscles, as he pointed his accusing gaze back and forth, between Gaspar and the ball, until Gaspar finally went and got it for him.

"Carry on, spaceman," the captain said, and continued on his way.

That's what Chumway says when he doesn't know a person's name and doesn't much care whether or not he has one — "Carry on, spaceman." It doesn't matter what gender the person he's talking to is, or even if the "spaceman's" species has gender.

Another time, we walked into a room and saw Last Gasp petting Spud. Petting him! Can you imagine? Dizzards don't purr when you pet them — they snarl. Besides, those spikes are sharp, and they leave itchy welts when you pull them out of your skin.

But there was the Gasper, petting the dizzard.

"Yup. Gettin' good and fat," Gaspar said, pretending he was talking to nobody in particular.

You'd think even Chumway would notice that Spud stayed hard and bony no matter how much he ate — but all the captain did was nod his head sagely and say, "Carry on, spaceman."

That's how it was, until the day the Old Man summoned Last Gasp and Spud to the bridge. Bill Felch, the ship's cook, had just delivered the captain's lunch and was still hanging around, holding this humongous, sharp knife he'd brought from the kitchen.

Belch (that's what we call the cook — never mind why) grinned as Chumway told Gasp about a report he'd received concerning Spud.

I'm not going to quote the captain directly, because he just went on and on and on, but the upshot of it was, to lay rumors to rest, he'd decided it was time to eat the dizzard.

Who, me? You think I'm the one that ratted on the Gasper? Just because I could smell Spud every night through the ventilator? Just because of all the times he rolled around in my bed, shedding spikes? Just because I once put bare feet into my best slippers and — eeeeyeccch! Like I said, humans shouldn't even think about that stuff!

What would you have done?

Last Gasp's eye darted toward Belch, who was fingering the knife. His chin trembled. A tear trickled down his cheek. He'd have been blubbering in another second, but just then, a cigar roach scuttled across the captain's plate.

"Yaaaaggghhh! Catch it! Kill it!"

Whap, whap, whap! Stomp, stomp, stomp!

Of course, the thing dodged every blow. And having spotted food, it was, as usual, just seconds away from asking a million of its closest friends over for lunch. It went scurrying off to post the invitations.

As it ran past Spud, Spud calmly reached out, picked it up, and ate it.

Whaddya know! Turns out cigar roaches can't hear a dizzard's brain waves, because dizzards don't have brains. Pure skull, clear through.

So that's how the captain found out what Spud really is. He's crew.

Since then, whenever we see Gaspar taking Spud for a walk — which really means dragging Spud by the leash — it's "Good morning, Mr. Spud" and "How do you do, Mr. Spud." And I have to treat Spud the same way Chumway does. And Spud doesn't even notice.

Then the captain glances at Last Gasp and says, "Carry on, spaceman."

What he thinks is Gaspar's status — passenger, crew, vermin, or food — is anybody's guess.