Feeding Frenzy

You must do this by playing through the Orville levels. The Shark King DOES NOT count toward this goal.

Easiest way to do it is get play a level that has mines in it. Grow to the biggest you can and then just eat sharks. When you are about to pass the level kill yourself. Again try to just eat sharks until you are about to finish it and kill yourself again. Just repeat this pattern. You can have a game over and use your continues just make sure you finish the level before the last life of your last continue. I got up to 100 sharks once using this strategy

Says what it is. Eat 1000 sharks. When you read this you might think to yourself "Well that's easy, I'll just replay the last level and keep eating the big evil shark guy". Apparently that doesn't count. Yes, it will show up in your foodbank I believe, but it doesn't count towards this achievement (from everything I've read). Therefore, if you're going to want this achievement, you're going to have to replay levels. Note: You must finish the level you're on for the sharks eaten to count towards the achievement (running out of all lives/continues will prevent it from registering).
1) Combine this achievement with 10 Hours, Frenzy Fanatic, and Shark Eater.
2) You can do one of two things. You can either just keep replaying through the game or you can keep replaying certain levels. I recommend altering between the two to make it less repetitive.
3) Start by working towards "Shark Eater" by replaying a level with Sharks in it. I recommend one that has "Mines" in it so that you can kill yourself before you beat the level so you can eat some more sharks with your plentiful lives. Level 37 is a good level to do this on. NOTE: YOU MUST BEAT THE LEVEL TO HAVE THE SHARKS COUNT TOWARDS THE ACHIEVEMENT. DO NOT LOSE ALL YOUR LIVES BEFORE BEATING THE LEVEL.
4) You don't get points in your foodbank while playing Time attack mode, so make sure you're in adventure mode.

Credit to lozzy for the sweet video which he linked in the comments and uses in the walkthrough.

ITS NOT THAT HARD

For those of you who think this is overwhelming, its really not. 1.5 - 3 hours guaranteed with this method.

1. Go to level 37, "Merry Go Round"
2. Grow 2 times as fast as possible, preferably without dying.
3. Float around avoiding eating anything but sharks. (especially do not eat the piranha power-up)
4. Before you complete the level kill yourself by either running into a bomb, or getting eaten by a clam shell
*NOTE: If you have the Safeguard power-up you cannot die by clam.
5. Repeat as many times as you wish, keep in mind that you have 2 continues that both reset you with 3 lives. (use all lives, continue, all lives, continue, then all lives for the biggest number of sharks in one run through)
*NOTE: You may want to finish the level with a few lives left just in case you actually die, if you get a game over without any continues remaining, the sharks you've eaten will not count.

You must complete the level for these to count towards your running total.

I hope this helped anyone who hasn't gotten this or passed on it because it seemed too overwhelming.

Best way to get this is to grind on the levels midway crossing and merry go round. when you're about to grow the next size after eating the sharks run into a mine and keep repeating until you're on your last life. when you have one life left beat the level and restart it. I found a good run gives you between 70 to 100 sharks eaten.

Note* don't waste your time on the shark king level as the sharks eaten in that do not count*

Note that you can kill yourself with seashells if there is no mines around, independent of your size. However watch out for pearls that bring your foodmeter over the top.

A trick I used to get massive lives is going to the 4th or 5th lvl with the 3rd fish, Big head small tail and a rod on its head. its the first time you meet the Killer whales and you can tail bite them... just bite their tail and go under before they turn around to eat you... I managed to get the chain all the way to 14000 points per bite.. giving an extra life to 2 lives per bite...( I believe its every 10,000 points gives an extra life or near it ) I went from 2 lives to 73 by the end of it..

I didnt mean to finish the level. I wanted to die but I was too gutsy and tried to push the bar as close to completion as possible..

doing this will allow you to do what other guides suggest with the mines to get anywhere from 400-500 sharks if not all 1000 in just 1 round. if you build enough lives.

Just want to say that while doing the method on Level 37 Merry Go Round, it is ok if you run out of both lives and continues.

I was playing and probably got up to 100+ sharks on my last continue and last life. I killed myself thinking that I still had another life but I didn't.

I was like "Oh shit, I just lost all of my kills!" Then before the Game Over screen popped up I got the Shark Eater achievement.

So that means you don't have to finish any of the levels for your fish or shark kills to count. They count even if you get the Game Over screen.

Merry Go Round is definitely the level that works best for this achievement as I just passed it using this level today. Another tip for this level is stay at the bottom of the screen until you grow to the size that allows you to eat sharks. A good share of the time the clams will give out free lives instead of pearls and you can get four or five more extra lives with this method at times which should see you eat an extra 30+ sharks per play through of the Merry Go Round level.