Ultimate Crawmad

The Ultimate Crawmad is the fifth major boss of Pikmin 4 (Wii U), found in Sandy Beach. It is a giant yellow crawmad that has purple dots on its shell and has red eyes. It somewhat resembles the Bug-Eyed Crawmad in both shape and size. Juvenile Ultimate Crawmads appear in Sandy Beach also and are fought as minibosses. The Ultimate Crawmad and its offspring stand out from other crawmads in that they spew poison from their mouths when agitated, in addition to the regular attacks they use to subdue their prey.

Olimar's notes

 * "A recent study has shown that a bigger species of crawmad had been discovered. They are commonly found in deep, large bodies of water. Like the majority of crawmads, it lies in the dirt waiting to ambush prey. If it is disturbed, it squirts poisonous saliva which poisons smaller creatures."

Strategy
Much like with the Bug-Eyed Crawmad, only its eyes are vulnerable, and when they both are significantly damaged the boss will flip over and reveal its vulnerable belly.