Salticidae

The Salticidae are a family of araneomorph spiders described by J. Blackwall in 1841. They are characterised by their ability to make great leaps (jumping spiders) and their good eyesight, one of the best among arthropods, abilities that they use to hunt or to move with great precision. With 636 genera and nearly 7,000 described species, approximately 13% of the total spider species, the Salticidae are the largest family.

They live in a wide variety of habitats. Although most species are found in tropical forests, they are also found in temperate forests, scrubland, deserts, etc., from the seashore to high mountains. The spider found at the highest altitude is a salticid, and the observation was made on an expedition to Everest.

They are generally very small spiders, with a lot of hair and a great variety of patterns and colours. We can distinguish them by their very characteristic eye pattern; they are 8 quite unequal eyes arranged in 3 rows. In the front row, the two central eyes stand out with an exceptional size. Looking at one of their large eyes, we can see how it changes colour; this happens because the retina, which is the darkest part of the eye, moves. They have very good vision, especially in these two front central eyes, which can create an image centred on the retina. It has been observed that they can have up to four different kinds of cellular receptors, with different absorption spectra, which gives them the possibility of tetrachromatic colour vision, with colour discrimination and a sensitivity that reaches the ultraviolet range.

It is worth highlighting the morphological evolution that some species have undergone, achieving shapes that make them look like ants, beetles, or pseudoscorpions, and some are confused with a root, a twig or a fragment of rock.

They are generally diurnal and very active hunters. In their legs they have a well-developed hydraulic system that acts by changing blood pressure. This allows them to jump without needing to have long legs like a lobster.

When they need to jump, they attach a silk thread to any surface and, if they fall for any reason, they can climb back up using the safety thread. They also use the silk thread to weave a kind of tent in which the females hide their eggs to protect them or as a shelter during moulting, a very delicate moment for any animal.

One of the behaviours that characterises salticids is their curiosity, which is further proof of their “intelligence”, meaning this level of intelligence at the appropriate level – we are talking about arthropods. If you approach a salticid and slowly bring your hand closer to it, you will be able to observe how it turns its head and its large eyes towards the object. This behaviour, which we can call “curious”, shows us that the animal is interested in what moves near you. They are one of the few spiders that can easily climb a glass. This is thanks to a tiny hair and hooks on their feet, which allow them to support themselves on the imperfections in the glass.

Salticids capture their prey by leaping onto it from a considerable distance, and can bounce from one place to another with great precision. In a good leap they can cover thirty times their body length. And they are capable of performing elaborate manoeuvres around obstacles to reach and catch their prey.

Vision also plays a very important role in their complex mating display. Males are usually quite different in appearance from females. They may have brightly coloured fur, feather-like hair, a kind of fringe on the front legs and other structures and modifications that attract attention.

All this ornamentation is essential in the visual courtship in which they ostentatiously display the painted or metallic parts of their body, making curious movements that we can describe as a kind of ritual dance. Observing this behavior it is easy to make comparisons with the nuptial displays of many birds.