Bessie Bass

Bessie Bass is a giant female Boss Bass (or actually a Big Bertha; see below), and is the middle boss in the third world of Yoshi's Island DS.

Yoshi's Island DS
When first encountered, Bessie Bass is only slightly larger than a Yoshi; though through the use of his magic, Kamek was able to grow Bessie to monstrous proportions.

In battle, Bessie attempts to attack Yoshi by crushing him with several small leaps out of the water or by making a giant jump out of the water. Then, she falls downward towards Yoshi with her jaws wide-open, trying to engulf him and leave Yoshi with Baby Mario floating away. It is only when Bessie makes one of these large leaps that she is vulnerable to an attack. While Bessie is in the air, Yoshi must hit her on the lips to injure her; hitting Bessie three times on the lips will be enough to defeat her.

In her battle against Yoshi, Bessie is assisted by several Tube Guys, whom Yoshi can swallow for eggs to fight her.

Trivia

 * It is unknown if Bessie is male or female - though the English name sounds feminine, and if female, Bessie would technically be a Big Bertha, the female counterpart of Boss Bass from Super Mario Bros. 3, which is of the same species and looks identical to Boss Bass (making her probably the only fish of the species in this game that is female, as the rest all seem to be Boss Basses).
 * Unlike the Big Berthas of Super Mario Bros. 3, though, Bessie cannot shoot young fish out of her mouth, and with her jumping abilities, behaves much more like the males of her species.