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Subphylum Chelicerata. Phylum Arthropoda. Characteristics. Their bodies are composed of two tagmata : Cephalothorax Abdomen Six pairs of cephalothoracic appendages that include: Mouthparts Pedipalps – sensory organs near mouth parts 4 pairs of walking legs No antennae
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Subphylum Chelicerata Phylum Arthropoda
Characteristics • Their bodies are composed of two tagmata: • Cephalothorax • Abdomen • Six pairs of cephalothoracic appendages that include: • Mouthparts • Pedipalps – sensory organs near mouth parts • 4 pairs of walking legs • No antennae • Suck liquid food from their prey
Classes Class Merostomata Class Phycnogonida Class Arachnida
Class Merostomata • Ancient group sometimes called “living fossils” • 2 subclasses: • Subclass Eurypterida • Subclass Xiphosurida
Subclass Euryterida Eurypterids, or water scorpions Extinct Largest fossil arthropods Abdomen has 12 segments and a spike like telson (last segment, or “tail”)
Subclass Xiphosurida Horseshoe crabs Ancient marine group Have an unsegmented horseshoe shape carapace (hard dorsal shield) and a broad abdomen Feeds on worms and small molluscs
Class Pycnogonida Sea spiders 1000 species known Range in length from 2mm - .75 m Contain 5 or 6 pairs of legs Males bear a subsidiary pair of legs (ovigers) in which they carry developed eggs (absent in females) Small head with a raised projection with a pair of simple eyes
Class Arachnida • Spiders, scorpians, ticks, mites, daddy longlegs etc. • Free-living • Common in warm, dry regions • 80,000 species – first arthropods to move into terrestrial habitats • Two tagmata: • Cephalothorax – head and thorax • Abdomen – may or may not be segmented, contain reproductive organs and respiratory organs • predators- have fangs, claws, venom glands or stingers
Dust Mite Tick Scorpion Spider
Class Arachnida Most arachnids are harmless to humans and actually do much good by destroying injurious insects. Feed by releasing digestive enzymes over or into their prey and then sucking the predigested liquid Few, such as black widows and brown recluse spiders, can give dangerous bites Scorpians can give painful stings Ticks and mites can be carriers of disease and cause annoyances or irritations. Mites can also damage a number of important food
Orders Order Araneae Order Scorpiones Order Opillones Order Acari
Order Araneae • Spiders • 40,000 species • Liquefies preys tissues with digestive fluid and sucks the resulting broth into its stomach • Use teeth to crush or chew prey • Have 8 simple eyes- used specifically for detecting movement (some, such as the jumping spider, can see images) • Contain 2 or 3 pairs of spinnerets (used to make webs)
Order Araneae • Reproduction: • Courtship rituals • Male spins a small web and deposits sperm on it and they picks up the sperm to be stored in special cavities of his pedipalps • When he mates, he inserts his pedipalps into the female genital opening to store the sperm in his mates seminal receptacles • Female lays her eggs in a silken net, which she may carry or attach to a web or plant • A cocoon may contain hundreds of eggs • Eggs will hatch in approximately 2 weeks • Young usually remain in the sac for a few weeks and molt once before leaving • Total molts range from 4-12 before reaching adulthood
Order Araneae Spiders are very timid creatures and are typically allies in the continuing battle with insects and other arthropod pests Venom used to kill prey is typically harmless to humans Poisonous spiders only bite when threatened Even tarantulas are NOT dangerous, they rarely bite and if they do are as serious as a bee sting However, the black widow and brown recluse can give serious to fatal bites
Order Scorpiones Scorpions Most ancient of terrestrial arthropods 1,400 species worldwide Common in tropical regions Generally secretive, hiding in burrows and under objects by day and feeding at night Feed on insects and spiders
Order Opiliones Harvestmen or “Daddy longlegs” 5,000 species Abdomen and cephalothorax are rounded Have only 2 eyes Not venomous and harmless to humans Unique because they are the only arachnids with a penis for direct transfer of sperm
Order Acari Ticks and mites Most medically and economically important group of arachnids 40,000 species have been described but scientists estimate 500,000 to 1 million species exist Mites are typically 1mm or less but some ticks can be 2mm-3cm Most are free-living
