Spinneret: the silk‑spinning organ of spiders and other arthropods

Structure and function

Each spinneret is made of movable segments and bears numerous microscopic spigots — tiny openings through which different silk proteins are released. Ducts link spinnerets to several specialized silk glands inside the abdomen. By using different glands or combining outputs, a spider can produce a range of silk types: strong core lines, sticky capture threads, soft wrapping silk and more.

Spinnerets are commonly described by position: anterior or posterior, and median or lateral. Their length and mobility vary by species. Some spiders possess a cribellum, a separate plate-like organ that produces a woolly silk, and others show reduced or modified spinnerets related to lifestyle.

Diversity, uses and biological importance

Spinnerets evolved to exploit silk’s versatility. Besides spiders, certain insect larvae (for example some caterpillars) have spinneret-like structures associated with labial glands to make cocoons. Silk produced via spinnerets serves many roles:

• web construction and prey capture,
• draglines and safety lines for movement,
• egg sac and cocoon construction,
• wrapping prey and producing reproductive or shelter structures.

Because spinneret number, arrangement and detail of spigots differ between groups, they are important characters in taxonomy and in understanding the evolutionary adaptation of silk use across arthropods. Spinnerets may also carry sensory hairs that help spiders guide and shape threads during spinning.