Nice job. Here is a list if ideas I'd like to throw at you to consider. How about:
- adding a counter to see how many starfish you eat.
- making it clear how the player fails (the game ended and restarted at some point but I wasnt sure what i did wrong? Is there a counter counting down that is added to when eating starfish?)
- moving obstacles to avoid (you could do horizontal/vertical/diagonal movement - each with different aquatic animals.
- different difficulty levels with more enemies/starfish at once (it's a bit easy as it is)
- having enemies periodically come in and chase you for a bit before leaving again. Might be fun and change up the gameplay a bit.
Otherwise is shows promise, well done!