This article is about Thresher Maws in general. For the page about the enemy called Thresher Maw, see Thresher Maw (enemy).

Thresher Maws are subterranean carnivores that spend their entire lives eating or searching for something to eat. They are enormous, violent creatures that burst up from the ground without warning when disturbed.

They reproduce via spores that can lie dormant for millennia and are robust enough to survive prolonged periods in deep space and atmospheric re-entry. As a result, thresher maw spores appear on many worlds, spread by previous generations of space travelers.

Biology

Thresher maws are solitary creatures; two or three at most can be found on a single planet. They live alone in nests spanning large areas underground. They can grow in excess of 30 metres tall above the ground, with a body nearly twice that size beneath the surface. The body of an adult thresher maw never entirely leaves the ground; only the head and tentacles erupt from the ground to attack.

Aggressive and highly territorial, thresher maws feed by absorbing significant quantities of solar radiation and survive best on planets, asteroids or moons with little or no atmosphere. They also consume minerals and ores from the ground itself for use in an unusual form of photosynthesis. This metabolic process, utilizing solar radiation and minerals as raw materials, creates the fuel that powers their various biological processes and allows them to move their significant mass with surprising speed.

Due to their size, and their burrowing method of movement, thresher maws are mostly immobile above ground, but can move at incredible velocities through subterranean environments. They can absorb a tremendous amount of damage and are very hard to kill. Their attacks consist of spitting a powerful, viscous acid that splashes on contact, burrowing up from beneath their prey, and smashing their targets with their claws in close range while emitting infra sound. Due to the overwhelming, direct physical nature of their attacks, shields are completely ineffective at mitigating any damage that is taken.

History

The Alliance first encountered threshers on the colony of Akuze in 2177. After contact was lost with the pioneer team, marine units were deployed to investigate. The shore parties were set upon by hungry threshers, and nearly the entire assault force was killed. Since then, thresher maws have been discovered throughout the galaxy, surviving even severely hazardous environments. Their physical and biological origins are unknown, although it is widely assumed they were "spread by a previous generation of space travelers", possibly before even the asari.

“This mission just got a lot more complicated.” — Spoilers for Mass Effect follow.

Mass Effect

If Commander Shepard has the Sole Survivor background, Shepard alone survived the thresher attack on Akuze. However, Shepard may later encounter a second survivor in the mission UNC: Dead Scientists, Corporal Toombs, who claims that a black-ops group called Cerberus caused the massacre at Akuze deliberately. He says Cerberus scientists wanted to study the thresher maws, so they let them kill not only the colonists, but the marine rescue team as well, to watch and study. Cerberus was delighted that Toombs survived and held him captive for years, using him for experiments. It is likely Toombs' story is true, as Cerberus used a similar technique six years later, luring Admiral Kahoku's marine team to their deaths in a thresher nest on Edolus.

Thresher Maws are encountered on a number of uncharted worlds. There is usually only one per planet, but some have two. They are usually encountered in the Mako, but can be fought on foot as well, though this is exceedingly dangerous. The Maws that are encountered can be bypassed if necessary. Planets known to have Thresher Maws are Antibaar, Chohe, Nepheron, Nonuel, Presrop, Xawin, Trebin and Edolus.

“The chances of surviving are… slim.” — Spoilers for Mass Effect 2 follow.

Mass Effect 2

Only one thresher maw is encountered in Mass Effect 2, on Tuchanka during the mission Grunt: Rite of Passage; it must be fought on foot. If the thresher is slain during Grunt's loyalty mission, Gatatog Uvenk informs Shepard that no krogan has slain a thresher maw on foot in generations; the last one to accomplish this feat was Urdnot Wrex. EDI also tells Shepard that defeating the thresher maw has generated several breeding requests for Grunt and even one for Shepard. Jubilant krogan in the Urdnot Camp will mention that they will be eating "thresher steaks" for months.

“There won't be an Earth left to save...” — Spoilers for Mass Effect 3 follow.

Mass Effect 3

In Mass Effect 3, the only thresher maw encountered is Kalros, a legendary thresher maw known as "the mother from which all other thresher maws spawn" and the largest thresher maw yet seen. A mural found within the ancient krogan city that Shepard explores prominently depicts Kalros, indicating that she is at least as old as the city itself.

She is summoned to attack a Reaper Destroyer that is guarding the Shroud on Tuchanka. After Shepard activates the maw hammers, Kalros attacks and defeats the Destroyer by coiling around it and pulling it into the ground, clearing the path to the Shroud.

See Also

• Cerberus Daily News
  • "Photo Revives Debate Over Tuchanka's 'Colossal Thresher Maw'" story

Trivia

• Thresher maws appear to be inspired by the giant sandworms of Frank Herbert's Dune. This is somewhat substantiated by the use of maw hammers in Mass Effect 3 to summon Kalros. Similar devices called "thumpers" were used to attract sandworms in the Dune novels.
• The Thresher Maw may also be inspired by the Sarlacc, a creature present in the Star Wars universe, as the two bear many similarities, particularly in terms of interplanetary migration.
• According to Javik, Thresher Maws were once small enough to be ridden.