Chelicerata Flashcards
What are the synapomorphies of Chelicerata?
-Chelicerae
-4 walking legs plus a pair of pedipalps
-two tagmata
-eight legs
-no mandibles/antennae
Describe Chelicerae
- Dorsal-ventrally opposed
- pinchers to mash up food
- in spiders they are modified to be venom infecting fang
What do the function of a chelicerate’s pedipalps depend on?
its lineage
Describe two tagmata?
-fused segments during embryogenesis which results in lots of small appendages that can be specialized
-cephalothorax
-abdomen; most are segmented but not spiders
What are the synapomorphies of merostomates?
- telson for steering
- hinge
- carapace
- opisthostoma: back half
- chilarium: scoopers that scoop food into their mouth
Describe the biology of merostomates
- aquatic
- massive carapace over their shells
- look like crustacea but they have pedipalps and chelicerae
- pedipalps & chelicerae are unmodified
- ancestral
- used for walking, pinching, and grabbing
- pinchers on them, similar to the crustacea
- Simple eye
- reminiscent of the median eye of crustaceans
- Telson for stirring
- controlling movement underwater
- Hinge used to protect the midsection
- book gills, leaf like flaps used for breathing
Describe the biology of pycnogonids
- sea spiders
- aquatic
- entirely marine
- micropredators
- dont eat the entirety of its prey just stab it and eat some of it
- proboscis
- has two straws: one for digestive enzymes & slurping out liquified parts of their prey
- eat starfish, worms, and protozeans
- in their larva form, the chelicerae has silk glands to attach to the male
- male has ovigers, which hold on to the brooding eggs
- paternal care of the young
- male has ovigers, which hold on to the brooding eggs
- pedipalp for eating and sensory
- fairly unmodified, not specialized
- highly reduced abdomen
- digestive system and reproductive system extends into their rear legs
Describe the biology of araneaens
- araneae: true spiders
- typical spiders seen are cobweb, corner spiders, or weaver spiders
- specialized to hunt a specific type of prey
- mimic that prey to get close
- peripheral, kleptoparasite animals that the spider would eat, but they stay out of reach and just eat the spider’s food
- pedicel
- strict separation of the cephalothorax and abdomen
How do spiders catch prey
-pursuit predators
-ambush predators
-can make a web
benefits and cons of pursuit predators
- benefit: higher likelihood of getting food
- con: high energy expenditure
benefits and cons ambush predators
- benefit: low energy expenditure
- con: low chance of getting food
describe the concept of creating a web
- can slurp it up
- create sheets of silk to save for later
- prey is mummified/ liquified
- gives way to kleptoparasites eating
How do spiders breathe?
- book lung for respiration
- leaf like halves in their abdomen
- reproductive & respiration system in the middle
- spinnerets at the end
- has lots of different glands to make silk
- venom glands in the front
How do spiders osmoregulate?
- keep water and keep salts
- pump water in the malphagian tubules and water flows by diffusion, waste, water & salt inside: rectal glands that pump back out salts that need to be kept
- coxal glands to excrete waste at the base of their legs
How do spiders sense their environment?
- use their pedipalps to sense prey
- 8 legs with hairs sensitive to vibrations
- use their pedipalps to tap on the ground as communication for mating and define territory
- placement of eyes are can give way to their vision
- side eyes for motion, middle eyes for color
- 8 eyes
- can also describe their species
- extended phenotype: can send and pick up messengers through silk that are attach to them (web sensing)
- some rely on visual signals
how do spiders reproduce?
- Male will often bring the female food, nuptial gift
- problem is, the female will eat the gift and still be hungry and could eventually eat the male
- uses the pedipalp to transfer spermatophore to the female
- some females will trick males
- say they didn’t mate just to eat them
What are the two kinds of venom spiders have?
cytotoxic, neurotoxic
Describe neurotoxic
- effects the nervous system
- prevent neurotransmitters from being received across a synapsis
- contract a muscle once, or a lot of times before dying
- systematic
- individuals die from suffocation
Describe the cytotoxic
- localized
- destroys tissues
- results in volcanic blisters
Where do spiders live?
- live in forests, underground, & houses
- sometimes when water floods the tunnels, spiders get pushed out
- diving bell spider can live underwater; has hairs around its book lungs to catch air and hold it
Describe the biology of scorpionida
- differ from spiders due to them having a post-abdominal tail called a telson
- has a stinger filled with venom
- Venom from a scorpion could possibly come from an immune system peptide
- They glow under UV light
- exoskeleton reflects uv light
- could see uv spectrum specs, and usually done to see each other in the night
- nocturnal
- only have a few eyes
- capture their prey usually at night
- they are good parents
- direct development
- maternal care
- after the eggs hatch they crawl on the back of the mother to be protected and fed
Describe the biology of solfugids
- camel spider, sun spiders, wind spiders
- inhabit deserts in the middle east
- long sensory pedipalps
- pedipalps are modified to be long antennae to tap the ground to sense what is in front of them
- not venomous
- fast
- nocturnal
camel spider vs regular spiders
- regular spiders secrete silk while camel spider do not
- both have a pedistal
- camel spiders are not venomous while regular spiders are not
- spiders have 8 eyes while camel spiders has less than 8
Describe the biology of opilliones
- harvestmen or daddy long legs
- pedipalps have spike for capturing prey
- tap in front of them for sensing
- paternal care of the eggs
- makes nests that are judged by the female
- in the winter they form massive clumps to keep warm
- most seen predator in the forest
- autonomy
- if you break off its leg, it will regrow during its next molt
- self-severing
- males with secrete silk around eggs
describe the biology of acarin ticks
- pedipalps used to detect where to pierce their prey
- heavily modifies forms of arachnids
- micropedators/ectoparasites
- capachilum
- includes their pedipalps (sensors) & cheilercae (modified into piercers)
- when they sense something they usually protect their chiercerae
- includes their pedipalps (sensors) & cheilercae (modified into piercers)
- has 3 hosts
- small (mouse) , middle (rabiit or fox), large (deer, humans, or cow)
- usually find their mate on their final host
- blood is used to make eggs
- has less chitin so it can expand
- anti-histamines (to stop immune reaction, dont want the host to know they are on there) and anti-coagulants
- Lyme disease carries the characteristic of a bullseyes rash
describe the biology of acarin mites
- microscopic
- smallest arachnids
- ectoparasites
- most of them are scavengers
- Phoresis
- transport parasitism
- not feed off the host, but using the host to move from one place to another
- new host , home, or for protection
- harmful
- larval mites have 6 legs while the adults have 8 legs
- Checkers
- red mites/red dots
- parasitic as larva
- when they bite, they secrete a toxin that turns the skin cells in to a hard plate, makes the skin turn into. straw
what do spiders understand
object permenance
what do butterflies have to avoid the from getting eaten by an orb spider?
scales
how does the bula spider catch prey
make a sticky glob, secrete a pheromone to attract moths, and throw it at the moth to eat
How do gladiator spiders make a small web?
web of 4 Corners from its leg and it waits for something to come directly under It
