ch 19: Trilobita and Chelicerata Flashcards
when did trilobites live?
Early Cambrian to the end of the Permian
why did trilobites go extinct?
in the largest extinction ever
what 3 sections did trilobites bodies have?
2 lateral and 1 axial
what type of eyes did trilobites have?
compound
what type of appendages did trilobites have?
biramous
trilobite larvae
planktonic
Chelicerata 2 tagmata
- cephalothorax
- abdomen
most anterior appendages in chelicerata are
chelicerae
2nd most anterior appendages in chelicerata
pedipalps
what are chelicerae used for
feeding
class merostomata = xyphosura =
horseshoe crabs
why are horseshoe crabs called living fossils
little has changed in their over 400 mill yr existence b/c it hasn’t needed to
where do xyphosura live?
shallow muddy ocean floor
what do merostomata eat?
worms, molluscs, etc
how do horseshoe crabs eat
swallow food in chunks and process it in a gizzard
3 ways a merostomata moves
- burrows
- walk
- swim upside down
carapace
protective shell like structure covering sometimes multiple tagmata
how is food in xyphosura shredded
using gnathobases at the armpits of their legs
horseshoe crab eyes
compound
horseshoe crab resp
book gills on underside of abdomen
xyphosura mating
orgy on shore
4 steps to horseshoe crab mating and birth/growth
- F lays eggs in pit
- M deposits sperm on top
- eggs hatch - direct development
- takes several molts to become an adult
class Eurypterids characteristics (3)
- went extinct in the Paleozoic
- incl the largest Arthropods to have ever lived
- sometimes come partially on land to feed (pioneers)
class Pycnogonida
sea spiders
Pycnogonids are exclusively
marine
sea spiders eat (3)
- sponges
- cnidarians
- echinoderms
pycnogonids movement
slowly, using their legs to cling onto things
how many pairs of walking legs do sea spiders have?
4
3 pycnogonid appendages
- ovigers
- palps
- chelicerae
ovigers in sea spiders
for cleaning and for males to carry the eggs
what do pycnogonids eat with
suck up food w/ proboscis
sea spider resp? excretion?
diffusion
class arachnida (4)
- spiders
- ticks
- mites
- scorpions
6 arachnida appendages
- chelicerae
- pedipalps
- 4 pairs of walking legs
arachnida eyes
ocelli
what 3 things do arachnida not have
- antennae
- mandibles
- compound eyes
order aranea
spiders
spider diet
carnivores
aranea carapace
covers cephalothorax
spider chelicerae are modified into
fangs
scopulae
broom-like tufts for adhesion
3 funct of pedipalps in spiders
- males use it to transfer spermatophore
- sensory
- holding prey
spinnerets
extrude silk
aranea resp
book lungs and trachea in epigastric furrow
aranea circ
open
centralized nervous system in spiders allows for
fast sensory processing and reflexes
2 main ganglia in spiders
- supraesophageal ganglion
- subesophageal ganglion
4 steps to spider eating
- trap prey in web or pounce onto it
- stab and poison w/ cheliceral fangs
- inject digestive enzymes
- sucking stomach draws in food
5 steps to spider mating and repro
- courtship (ensures male is not eaten/is fit)
- male used pedipalp to pass spermatophore into female’s receptacle
- F spins special cocoon for eggs
- F guards cocoon and spiderlings after emergence sometimes also
- spiderlings disperse via wind
spider development
direct
how many spider spp’s venom is actually dangerous to humans
20-30
what protein is spider silk made of
fibroin
how do spiders prevent their silk from solidifying until out of body
store in lipid bags
silk can be specified into at least 6 diff types
- 2x eggs
- anchor a dragline
- radial
- spiral
- catching prey
silk strength
as strong as nylon - can stretch up to 130% before breaking
are web design characteristics learned or genetic?
genetic
5 common spider families
- funnel web spiders
- orb-web spinners
- wolf spiders
- crab spiders
- jumping spiders
wolf spider females
carry spiderlings
crab spider characteristics (3)
- ambushers who wait on flowers/leaves
- often white/yellow
- suck food thru tiny punctures (look unharmed after)
jumping spiders sharacteristics (2)
- developed ocelli
- active in daytime
3 differences of scorpions from spiders
- big pincers on pedipalps for seizing and tearing prey
- small pincers on chelicerae
- stinger for defense
3 characteristics of scorpions
- nocturnal hunters
- eyes not well developed
- thought to have arisen from aquatic ancestors
how do scorpions detect prey
feel body movements with body hairs, and ground vibrations with pectines
4 steps to scorpion mating/repro
- mating ritual dance
- male drops a spermatophore and then dances F over it to int fert
- direct development
- parental care
order acari
ticks, mites
4 ways acari anatomy has been simplified (due to their small size)
- no tagmata
- often no segments
- often no heart or resp syst
- brain indistinct from other ganglion
mite spp weird life history
single male fert all his sisters in the womb then born dead
3 types of mites that are agri pests
- spider mites
- tracheal mires (honey bee colonies)
- Varroa mite (honey bee nests
4 mites who impact mammal health
- scabies (mites drill under skin and leave itchy rashes)
- mange and ear mites (domestic and wild animals)
- dust allergy = allergy to proteins in mites feces
- chigger mites leave itchy bites
ticks vs mites
ticks are larger blood sucking versions
6 diseases ticks can transmit to humans and domestic animals
- lyme disease
- tick paralysis
- tape worms
- nematodes
- rocky mtn spotted feaver
- typhus
order opiliones = harvestmen =
daddy longlegs
what don’t harvestmen have (2)
- venom glands
- multiple tagmata
how do daddy longlegs deter predation
repugnatorial glands
female opiliones lay eggs thru
ovipositor
pseudoscorpiones silk glands
at mouth, not butt
pseudoscorpiones venom gland location
pincers
do pseudoscorpiones have a stinger?
no
solpugids jaws
munching (up and down) for hunting termites at night
