Gohma

In Ocarina of Time
The mother of all arachnids inside the first dungeon and the "curse" placed upon the Great Deku Tree, Queen Gohma, the Parasitic Armored Arachinid, is your first boss in OoT. Not so hard as you might think, Queen Gohma's only weakness is her eye when it turns red, but don't just rejoice, not for nothing her title reads "armored" and anywhere else (even her normal eye) but the red eye will result in a useless attack from you. She has just two ways of attacking you: one is the very first thing she does when the fight begins, Queen Gohma will climb into the ceiling, and from there lay some eggs into the ground (Just before laying the eggs her eye will turn red). The eggs will turn into Gohma Larvae if you're not fast enough to destroy them before they hatch. The Gohma Larvae, as you might know from previous experience inside the dungeon, attack in only one way: when their eye turns red, they will attack by jumping towards you. The second way is by walking menacingly towards you and hit you with her pincers (Again just before she does this, she will "stand up", scream and turn her eye red). As soon as you enter the room, whip out your slingshot and Z-Target her eye. When it turns red, shoot it and she will be stunned for a few moments. This gives you the opportunity to hack away with your Kokiri Sword. If you don't defeat her the first time, Z-target her again as soon as she get up, and wait until she's up on the ceiling. She will try to unleash her babies on you; when her eye turns red, unload with your slingshot. However if the babies still come, Z-target them and defeat them quickly. When Queen Gohma comes back down, continue with the same pattern as before to defeat her and earn your prize: a Heart Container and the Spirtual Stone of Forest, the Kokiri Emerald, which the Great Deku Tree will give to you.

In The Wind Waker
Gohma is causing much discomfort to Valoo in Dragon Roost Cavern in The Wind Waker. Gohma is covered in a hard shell. First, use your grappling hook on Valoo's tail that is sticking out of the ceiling and the cieling will cave in, breaking Gohma's shell. After a few times, the shell will be broken leaving him/her vulnerable. Use the grappling hook on Gohma's eye to bring it down to your level and attack with your sword to defeat it. In The Wind Waker, you must defeat Gohma twice, once in Dragon Roost Cavern and once in Ganon's Castle to complete the game.