Animals such as flies, spiders, and geckos can adhere to and move along vertical surfaces and ceilings due to specialized attachment mechanisms involving patterned surface structures. These structures interact with the substrate's profile, and their effectiveness scales with body size. Microscopic studies show that smaller animals like flies use micrometer-sized setae, while larger animals like geckos require sub-micrometer structures for adhesion. This scaling is explained by contact mechanics, where splitting contact into smaller subcontacts increases adhesion. Attachment structures have evolved independently in various animal groups, including insects, spiders, and lizards. These structures consist of fine patterns of protuberances, with different types of setae in various species. The adhesion mechanism is attributed to molecular interactions and capillary forces, or purely van der Waals interactions. Recent studies suggest that gecko setae adhesion is due to van der Waals forces, and that splitting contact into smaller subcontacts enhances adhesion. The terminal elements of setae in animals range from 0.2 to 5.0 micrometers. The areal density of these elements increases with body mass, following a logarithmic relationship. This scaling is explained by contact mechanics, where the adhesion force is proportional to the linear dimension of the contact. By splitting the contact into smaller subcontacts, the total adhesion force increases. The study combines microscopic observations with contact mechanics to explain the scaling of attachment devices across different animal sizes. The results show that the adhesion force scales with the body mass, and that the contact radius and seta density adjust accordingly. The findings suggest that contact splitting is a key design principle in biological attachment systems. The study also highlights the importance of patterned surfaces in providing reliable contact on various surfaces and increased tolerance to defects. The results demonstrate that contact splitting is a fundamental principle in the evolutionary design of biological attachment systems.Animals such as flies, spiders, and geckos can adhere to and move along vertical surfaces and ceilings due to specialized attachment mechanisms involving patterned surface structures. These structures interact with the substrate's profile, and their effectiveness scales with body size. Microscopic studies show that smaller animals like flies use micrometer-sized setae, while larger animals like geckos require sub-micrometer structures for adhesion. This scaling is explained by contact mechanics, where splitting contact into smaller subcontacts increases adhesion. Attachment structures have evolved independently in various animal groups, including insects, spiders, and lizards. These structures consist of fine patterns of protuberances, with different types of setae in various species. The adhesion mechanism is attributed to molecular interactions and capillary forces, or purely van der Waals interactions. Recent studies suggest that gecko setae adhesion is due to van der Waals forces, and that splitting contact into smaller subcontacts enhances adhesion. The terminal elements of setae in animals range from 0.2 to 5.0 micrometers. The areal density of these elements increases with body mass, following a logarithmic relationship. This scaling is explained by contact mechanics, where the adhesion force is proportional to the linear dimension of the contact. By splitting the contact into smaller subcontacts, the total adhesion force increases. The study combines microscopic observations with contact mechanics to explain the scaling of attachment devices across different animal sizes. The results show that the adhesion force scales with the body mass, and that the contact radius and seta density adjust accordingly. The findings suggest that contact splitting is a key design principle in biological attachment systems. The study also highlights the importance of patterned surfaces in providing reliable contact on various surfaces and increased tolerance to defects. The results demonstrate that contact splitting is a fundamental principle in the evolutionary design of biological attachment systems.