Arachnids
Arachnida
Classification
- Phylum: Arthropoda
- Subphylum: Chelicerata
- Class: Arachnida
Pronunciation
How to pronounce Arachnida: /əˈræknɪdə/
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Images
Summary
Arachnida is a diverse class of arthropods known for their eight legs and distinct body structure, including spiders, scorpions, ticks, and mites. They play important ecological roles in terrestrial environments and exhibit a wide range of behaviors and diets.
Physical Characteristics
Adult arachnids have eight legs and two additional pairs of appendages adapted for feeding and sensory functions. They lack antennae and wings. The body is organized into two main segments: the prosoma (cephalothorax) and the opisthosoma (abdomen).
Identification Tips
Look for the presence of eight legs and chelicerae. Unlike insects, arachnids do not have wings or antennae.
Habitat
Most arachnids are terrestrial, but some can be found in freshwater and marine environments.
Distribution
Globally distributed with over 110,000 named species, found in diverse habitats except for the pelagic zone.
Diet
Mostly carnivorous, feeding on pre-digested bodies of insects and other small animals. Some are parasites or omnivores.
Life Cycle
Reproduction typically involves laying yolky eggs that hatch into immature forms resembling adults, although scorpions may bear live young. Mites can also be ovoviviparous or viviparous.
Reproduction
Males transfer sperm to females via spermatophores. Complex courtship rituals exist in many species, and only females usually provide parental care.
Predators
Arachnids have various natural predators, including birds, amphibians, reptiles, and other arthropods.
Ecosystem Role
They play crucial roles as predators in their ecosystems, contributing to pest control and decomposing roles in the food web.
Cultural Significance
The term 'arachnid' is derived from the Greek myth of Arachne, emphasizing the cultural perception of spiders and their complex relationship with humans.
Health Concerns
Some arachnids, particularly ticks and certain spiders, can be vectors for diseases or cause allergic reactions, but general concerns vary by species.
Collecting Methods
- Pitfall traps
- Hand collecting
- Sweep nets
- Sticky traps
Preservation Methods
- Ethanol
- Drying
- Freezing
- Embedding in resin
Evolution
Arachnids are part of the subphylum Chelicerata, sharing a common ancestry with other arthropods and showing significant evolutionary adaptations to terrestrial life.
Similar Taxa
Misconceptions
Many people believe all arachnids are dangerous or harmful; however, most species are harmless to humans.
Tags
- Arachnids
- Arachnida
- Spiders
- Ticks
- Mites
- Scorpions