Opisthothelae

Opisthothelae

Opisthothelae is a suborder of spiders within the order Araneae. This suborder is one of the two main divisions of spiders, the other being Mesothelae. Opisthothelae is further divided into two infraorders: Mygalomorphae and Araneomorphae. These spiders are characterized by their advanced silk-spinning capabilities and diverse ecological adaptations.

Taxonomy

Opisthothelae is a well-defined suborder that includes the majority of spider species. It is divided into two infraorders:

• Mygalomorphae: This infraorder includes spiders such as tarantulas and trapdoor spiders. Mygalomorphs are generally characterized by their robust bodies and downward-facing fangs.

• Araneomorphae: This is the largest infraorder of spiders, including the majority of spider species. Araneomorphs are distinguished by their more advanced web-building techniques and diverse hunting strategies.

Morphology

Opisthothelae spiders exhibit a wide range of morphological features, but they share some common characteristics that distinguish them from Mesothelae:

• Silk Production: Opisthothelae spiders have highly developed silk glands and spinnerets, allowing them to produce a variety of silk types for different purposes, such as web construction, prey capture, and egg protection.

• Fang Orientation: In Mygalomorphae, the fangs are oriented parallel to the body axis, while in Araneomorphae, the fangs are oriented diagonally, allowing for more efficient prey capture.

• Respiratory System: Most Opisthothelae have book lungs, but some Araneomorphae have evolved tracheal systems for respiration.

Behavior and Ecology

Opisthothelae spiders exhibit a wide range of behaviors and ecological adaptations:

• Web Construction: Many Araneomorphae are known for their intricate web designs, such as orb webs, funnel webs, and sheet webs. These webs are used for capturing prey and as a habitat.

• Hunting Strategies: Some Opisthothelae, particularly in the Araneomorphae, are active hunters that do not rely on webs. They may use ambush tactics or actively pursue prey.

• Venom: Opisthothelae spiders possess venom glands that they use to subdue prey. The potency and composition of the venom vary widely among species.

Evolutionary Significance

The diversification of Opisthothelae is a significant event in the evolutionary history of spiders. The development of advanced silk-spinning capabilities and diverse ecological niches has allowed them to become one of the most successful groups of arachnids.

Also see

• Araneae
• Mygalomorphae
• Araneomorphae
• Spider anatomy
• Spider behavior

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