Tentacle

Tentacle=

Big Tentacle=

Baby Tentacle=

"BIOLOGY IS DISGUSTING."

- WX-78

Tentacles are hostile Monsters that specifically spawn in Marshes or Caves, though they will not spawn on world-generated roads. Wickerbottom can summon Tentacles using one of her self-published books.

When you get close enough, black bubbles will pop out of the spawn point of tentacles. Then they will appear as purple spotted tentacles spiked at the tips, which will emit growls and come out of the ground to attack anything that comes close enough.

Tentacles take three blasts from the Ice Staff to be frozen and cannot be put to sleep or set on Fire. When killed, they will drop 2 Monster Meat and can drop a Tentacle Spike or Tentacle Spots.

Big Tentacle
The Big Tentacle, also known as Tentapillar, is a large section of Tentacle that appears underground, going up into the surface. Attacking it will cause several smaller Tentacles to spawn around it, which will focus their attack on the player but are weak and will die from one hit from a Spear. When defeated, the Big Tentacle will retreat into its hole, causing an Earthquake and dropping a variety of items, some of which are limited to a number per day across all Big Tentacles.

With normal damage modifier characters, Tentacles and Big Tentacles take 15 hits with a Spear, 12 with a Bat Bat, 10 with a Tentacle Spike, 9 with a Ham Bat and Thulecite Club, and 8 with Dark Sword to be killed. The hole that remains after a Big Tentacle has been defeated can be attacked, with a chance of it spawning another Big Tentacle.

Baby Tentacle
Whenever the Big Tentacle is attacked, it will spawn several "Baby" Tentacles, with every hit on the Big Tentacle spawning groups of them at a time. These tentacles are smaller than regular Tentacles and only take one hit from a Spear to be killed. They do not drop anything, as they are there only to protect the Big Tentacle. They also lack the spikes that the regular Tentacles have, though they still sport the telltale bumps in the ground when they're about to come out.

If the Big Tentacle and the Baby Tentacles aren't attacked for a while, the small ones eventually retreat back into the ground. Baby Tentacles are found only in caves.

Behavior
Tentacles are very dangerous because of their high damage and health. A careless player might walk straight into an area with many Tentacles and get trapped. They can only be seen once a creature or character gets relatively close.

At first, there will be a barely noticeable bubbling patch on the ground, followed by a piece of tentacle that looks like a purple bubble, which appears just before the Tentacle appears. When a creature is in range, the Tentacle will emerge and twirl around once before snapping and standing straight up. There is a brief delay before it will strike again.

If its target moves out of range, the Tentacle will sink back down into the ground; it cannot move around and give chase. After going back underground, Tentacles will stay hidden until any target moves in range or directly hits them, at which point they begin to attack again.

Due to their aggressive nature, it is common to find drops from creatures they kill or from dead Tentacles killed by other creatures (usually Merms) lying on the Swamps. They can kill a group of 4 Spiders on their own, many times, though it depends on the situation.

Hunting
Tentacles cannot be stunlocked. It takes 15 strikes with a Spear with most characters to kill one. If properly timed, they can be attacked in between their strikes. Although they appear to have an area attack, Tentacles actually attack targets individually. Due to this limitation, Pigs that attack if they get too close can easily kill a Tentacle if there are at least three of them.

Tentacles will still produce an insanity aura, even if is still in the ground and out of attack range. Thus, the sanity meter is a good indication that a Tentacle is near. Additionally, there is a low growl that can be heard when a Tentacle is near, and the player can watch for the bubbling patch, though Sanity drain is still the best indication.

A safe but time-consuming way to fight a Tentacle is to go right next to the spot where the Tentacle will come out, hit it as soon as the little nub appears, and dash to the side, out of its reach. Repeat after the Tentacle retracts into the ground.

It can be easy to kill Tentacles with little or no work by finding some Rundown Houses, waiting for dusk, and seeing if the Tentacle alarms the Merms. The stiff fight will end in Frog Legs, Monster Meat, Fish, and perhaps Tentacle Spots or a Tentacle Spike.

To make "tentacle traps" bring several pine cones to the swamp and plant 4-6 of them around where the tentacle emerges. once the trees are grown and your ready to harvest the tentacle approach it so it will emerge then light the trees on fire. This method of hunting is easiest with Willow.

Trivia

 * If the player is near a Swamp biome, the Tentacle can appear (rarely) outside of its biome.
 * Tentacles are creatures that are believed to be created by Maxwell, as he shows some concern that the Tentacles have been reproducing, something he may not have planned to happen.
 * When using the Thulecite Club, there is a chance that small Shadow Tentacles will appear and assist the player with attacking.
 * Maxwell expresses surprise at the existence of the Big Tentacle and the baby Tentacles, suggesting that the Tentacles are reproducing, and not planned to do so, as Wilson and Wickerbottom mention that Tentacle Spots are its genitalia; supported by Maxwell's quote for Tentacle Spots, 'This is how they reproduce'.
 * The small tentacles that appear around the Big Tentacle used to be colored green.
 * In the script that handles the Tentapillar's emergence when the hole is attacked, there is a note/Easter Egg that says: ("Hit calls cthulhu"). This is a reference to a story by H.P. Lovecraft called "The Call of Cthulhu".
 * The script refers to the "baby tentacles" as arms, suggesting they are from the same entity.