Twilit Bloat

The Twilit Bloat is a mini-boss appearing in Twilight Princess. This creature is a bloated, giant Shadow Insect with tentacles emerging from its abdomen that can release electric shockwaves. This larger variant has the unique ability to swim underwater. Judging by its size and status as a mini-boss, it is plausible that this variant is the Queen of the Shadow Insects, as queen insects are characteristically larger to enable reproduction.

Once Link obtains fifteen Tears of Light in the Lanayru Province, the Twilit Bloat will appear on Lake Hylia, holding the last Tear of Light.

Strategy
To defeat Twilit Bloat, Link must wait until it isn't charging him or is bursting with electricity. He must then L-target it and leap onto its lower section, then proceeding to hold the L button and repeatedly press A to bite it furiously. The young hero must repeat these steps a few more times and it will eventually fall into the water, lying on its back. At this point, Link must jump on its belly and use the energy field with Midna's help to attack its six tentacles at the same time. Once they are all destroyed in the same instant, it will shrivel up and die. This will release the last tear of light Link will collect, allowing him to finish returning light to Hyrule.

Trivia

 * The Twilit Bloat highly resembles a type of real-life sea crustacean known as a giant isopod.