Cannibalism in the Womb!

Hello Readers,

When I started this blog I totally said that it was going to be a place to "share my reservoir of knowledge and random comments". Well total fail on that because I've been having many random observations and not sharing them. Perhaps it's because I'm lazy, or maybe I'm just waiting for very epic things to come along but I have certainly not been sharing my reservoir of knowledge.

If I want to form this blog into something sustainable, then I need to start writing about the less epic, and likely less lengthy, random events in my life.

The title hopefully grabbed your attention. I know you're dying to know what I'm talking about. A couple days ago I was reading National Geographic, the November issue, when I came across the following picture and caption:

A sand tiger shark off the Bonin Islands will soon give birth. During
the nine-month pregnancy, the largest two pups will have eaten their
siblings for sustenance, a kind of cannibalism unique to this species.

Source: National Geographic Archives - see 10th picture in the slide, second page

I just knew I had to do some research into this, because well:

1. It says during pregnancy, so they eat each other while still inside the mother?? and ...
2. (OK, This took me a while to realize so don't feel embarrassed if it didn't click for you immediately) Hello, sharks are fish! What the hell is a shark doing pregnant? Fish lay eggs!

With these questions in mind I went to work. What is the natural place to conduct my research? Wikipedia of course. I've linked everything up but if you're too lazy to look, here's what I've discovered:

• Sand tiger sharks are also called grey nurse sharks. (reason unknown)
• The species practices vivipary, which means that the embryo develops inside the mother, eventually leading to a live birth, i.e. eggs kind of hatch inside the mother and the young grow up there for a while.
• Female sand tiger sharks have two uteri.
• The shark babies (called pups) develop and will eat yolk sac, and each other, until only one is left, in each uterus.
• The eggs do hatch inside the mother for most sharks (apparently) but only with the sand tiger sharks do pups go all "cannibal" before they're even "born"

Crazy, I know! Now unfortunately I can't think of any cool ways to work this tidbit of knowledge into a conversation with friends or family: "Hey, so I know an animal that will eat it's own kind at -2 months old!" or "Good thing we're not sand tiger sharks. You think school bullying is bad ... ..." might work. If you think of any other ways let me know. :)

p.s. I'd like to thank Shannon for the National Geographic subscription. True I'm still on November but I'm loving it. I'm actually being super geeky by highlighting in it (with a ruler because I don't want wobbly lines in my Nat. Geo.)