1. Overview

1.1 Introduction

1.2 The arachnid orders

1.3 Material and methods

1.4 Terminology

1.5 Summary and distribution of attachment principles among arachnids

2 Mechanical attachment devices

2.1 Claws

2.2 Spines and pointed hairs

2.3 Other interlocking devices

2.4 Pincers and clamps

2.5 Expansion anchors

2.6 Lock-and-key

2.7 Wrapping

3 Tape- and spatula-shaped microstructures

3.1 Introduction

3.2 Spatulate setae

3.3 Spatulate microtrichia

3.4 Spatulate surface structures

3.5 Micro-tapes

4 Nano-Fibrils

4.1 Cribellate and aciniform silk

4.2 Particle catching setae

4.3 Fibrillar locomotory pads lacking spatulae

5 Mushroom-shaped microstructures

5.1 Introduction

5.2 Cuticular mushroom-shaped microstructures

5.3 Mushroom shaped secretion products

6 Suction cups

6.1 Introduction

6.2 Adanal suckers in mites

6.3 Sucker-like mouth parts

7 Soft adhesive pads

7.1 Introduction

7.2 Cushion-like arolium

7.3 Disc-like arolium

7.4 Transverse lip arolium

7.5 Other smooth adhesive pads

8 Adhesive secretions

8.1 Introduction

8.2 Viscid glue

8.3 Solidifying glue

9 Biological function and evolutionary aspects

9.1 Ontogeny and the role of maternal care

9.2 Dispersal

9.3. Microhabitat access and climbing demand

9.4 Herbivore-plant interaction

9.5 Predator-prey interaction

9.6 Parasite-host interaction

9.7 Sexual selection

10 Comparative contact mechanics

10.1 Comparative mechanics and strength of smooth and structured adhesive foot pads

10.2 The contact splitting theory and the scaling of adhesive foot pads 10.3 Dry or wet adhesion?<

11 Biomimetics: What can we learn from arachnids?

11.1 Why geckoes are not unique

11.2 Noteworthy structures and their potential for biomimetics and bioinspiration

This book surveys attachment structures and adhesive secretions occurring in this class of animals and discusses the relationships between structure, properties, and function in the context of evolutionary trends, and biomimetic potential. Topics comprise mechanical attachment devices, such as clamps, claws, hooks, spines and wraps, as well as hairy and smooth adhesive pads, nano-fibrils, suction cups, and viscid and solidifying adhesives. Attachment is one of the major types of interactions between an organism and its environment. There are numerous studies that deal with this phenomenon in lizards, frogs, insects, barnacles, mussels and echinoderms, but the second largest class of animals, the Arachnida, was highly neglected so far. The authors demonstrated that most arachnid adhesive structures are highly analogous to those of insects and vertebrates, but there are also numerous unique developments with some intriguing working principles. Because arachnid attachment organs have a very strong potential of technological ideas for the development of new materials and systems, inspirations from biology could also be interesting for a broad range of topics in materials and surface engineering.