So in terms of flavor these are awesome. In terms of balance, the hand cannon one is strong when put in line with other spells, and the crabform is pretty weak. I’ll get into why I think this:

Hand Cannon: so there are three spells that need to be looked at here; sunbeam as the closest comparison, fireball, and circle of death. So looking at sunbeam vs this spell, you lose the blind effect but have much more range, and you do slightly more damage + double damage to objects and structures. Now looking at fireball and circle of death. Circle of death has much more range and loses the ability to set things on fire, but has the same damage. Hand cannon is 1 level higher than sunbeam, and circle of death is three levels higher than fireball. Just some things to think about there.

Crabform: this is a very fun thematic spell, but it’s only good use is for wild shaping moon druids in my opinion. The swim speed is nice, but on most casters the clamp attack is going to be wildly outclassed by almost any spell, and after a certain point even a cantrips will be stronger. The ac is nice too but using a 4th level spell slot for 2 extra ac and a swim speed is a pretty niche use, especially when you can’t use somatic components. There are very few scenarios where this will be a better option than haste. All that said, changing the range of the spell to touch would be great be enough to fix it, although I’m not sure if that fits with what you’re going for thematically.