I searched the web and found this response to someone else's cry about deformed carrots."Life is too good for your carrots. I would guess that there are too many nutrients, which is what causes them to split. You can remedy that by not ammending the soil, like not adding in compost or manure before you plant them, and also by mixing in sand, which will help them to grow straighter, too.
I know this is an older entry, and I don't know if you're still in search of an answer, but I came across this and figured I'd pitch in. That kind of carrot deformation is usually a symptom of root-knot nematodes in the soil. They won't hurt the quality of the carrot, but they will stunt it's growth and make it bizarrely shaped. Usually, crop rotation will cut down on their appearance, but if you have a serious problem, consider ordering beneficial nematodes from an organic gardening place. Putting the good kind in the soil will reduce the appearance of the bad kind!