Daddy Long Legs

Daddy Long Legs are a significant midgame threat. They appear as floating bulbous masses covered in X's with long tentacles, and will devour any moving creature they can, including slugcat of course. Daddy Long Legs are all blind, however, and will only react to sounds. Softer sounds may cause them to reach out with a tentacle, while louder impacts will cause a Daddy Long Legs to aggressively pursue the noise.

If the player is grabbed by a tentacle, slugcat will be unable to struggle free. The player can free themselves by throwing a rock or a spear at the tentacle grabbing them. If the player is unable to free themselves, the Daddy Long Legs will slowly drag its prey to its core and swallow it whole. Daddy Long Legs can be killed by dealing significant damage to the core, but this is a difficult prospect since its tentacles will tend to get in the way. Sneaking by or outrunning these threats is typically the optimal solution.

Subtypes
There are three distinct varieties of Daddy Long Legs:

Brown Daddy Long Legs
Also known as "Brother Long Legs", these less threatening varieties are found in central Garbage Wastes and will likely be the first variety new players see. They are slower, smaller, and possess less tentacles than their blue brothers. They appear to emerge from a central pool of water, but have no difficulty navigating through midair.

In hardmode proto versions of these can be found in the garbage wastes.

Blue Daddy Long Legs
The main threat, Blue Daddy Long Legs are larger and more aggressive than their brown counterparts. They are found in The Exterior and in Five Pebbles, and will likely be a significant obstacle to the player in these locations.

Proto Daddy Long Legs
Found exclusively in Five Pebbles: Unfortunate Development, these stationary threats cover certain walls in the area. Although not mobile, they may still possess short ensnaring tentacles, and will devour slugcat should they stray too close. Escape is not a likely option once trapped by these, so the player should make every effort to avoid them.

Tips

 * When a Daddy Long Legs hears a noise, the X symbols on its core will light up slightly. This is useful for figuring out where it is likely moving towards.
 * Throwing a rock at a tentacle will stun it briefly, while throwing a spear at it will permanently disable it. Either attack will alert the Daddy Long Legs to your presence, however, so the player must be prepared to move quickly if they do so.
 * Throwing a rock at a wall is an easy way to create a distraction. The noise is typically loud enough that the Daddy Long Legs will go to that location and search around it for a short time. Be wary not to hit a tentacle when doing so, however, as this may simply cause the Daddy Long Legs to find you more quickly!
 * If all of a Daddy Long Legs' tentacles are disabled via spear, it will fall to the ground and writhe uselessly. Be aware that its core can still eat you, of course.
 * Climbing poles and walking on flat terrain does not seem to create any noise. Landing on the ground from even small jumps will create noise, as will most thrown objects.

Trivia

 * Lizards, scavengers, and other beasts seem to regard the daddy long legs as significant threats, and will tend to run away from them.
 * Daddy Long Legs seem to have been created by Five Pebbles. It is unknown whether they were created intentionally, as an accident, or as a byproduct from some other experiment, but they seem to have some corrupting influence on him.
 * Developer commentary on the design of this creature and those like monster water kelp can be found here.
 * Their sandbox unlock is found on hardmode in Unfortunate Developement.