Ch 28 Arthropods Flashcards
1
Q
How diverse are arthropods
A
- Very numerous and diverse group of animals
- Over 1,000,000 species
2
Q
what are the 4 phyla of arthropods
A
- Trilobita: A very old and now extinct group containing trilobites
- Chelicerata: Spiders, ticks, mites, scorpions, horse-shoe crabs
- Crustacea: Crabs, shrimp, lobster, etc
- Uniramia: Centipedes, millipeds, insects, etc
3
Q
how do arthropods first arise
A
- appeared over 600 million years ago
- first terrestrial animals
- little known about how they began, probably the earliest were similar to trilobites: thick outer body with many segments and paired appendages with a feathery gill and walking leg
- modern arthropods have lost many segments and have become more specialized
4
Q
what is the basic form and function of arthropods
A
- varies a lot
- 3 shared characteristics
- tough exoskeleton
- series of jointed appendages
- segmented body
- typically have a brain, ventral nerve cord, and open circulatory system with 1 heart
5
Q
what is the arthropod body plan
A
- exoskeleton made typically of chitin, can be leathery and flexible, or hard and rigid
- in terrestrial arthropods the exoskeleton is water proof
- restricts growth and movement (they can only move at joints)
- have multiple jointed appendages that are specialized, ex antennae, claws, legs, wings, flippers, etc
- multiple segments, can be many or few
6
Q
how do arthropods feed
A
- evolved in various ways to eat pretty much anything
- specialists or generalists
- structures for carnivory, herbivory, detritus feeding, filter feeding, internal parasitism or external parasitism
7
Q
how do arthropods breath
A
- gills
- book gills or book lungs
- tracheal tubes
- many aquatic arthropods like crabs have feathery gills formed from part of the mouth or legs
- book gills are found in horseshoe crabs
- book lungs found in spiders and their relatives
- book lungs and book gills are both layers of tissue like a book that are in a sac (for lungs) or under the body (for gills)
- Spiracles are tubes used in respiration connected to the outside
- movement causes tracheal tubes to contract, pumping O2
8
Q
how do arthropods do internal transport
A
- in arthropods a well developed heart pumps through an open circulatory system
- in spiders and some insects the heart is long and narrow and lies along the abdomen
- in lobsters and crayfish the heart is smaller
9
Q
how do arthropods excrete
A
- anus for digested materials
- in terrestrial species malpighian tubules remove waste from blood in sinuses, then add to undigested waste
- may have small glands
- diffusion for aquatic taxa
- through gills
10
Q
how do arthropods do response
A
- well developed
- brain formed from ganglia
- nerve cord
- ganglia lie in various segments
- statocysts and chem receptors
- compound eyes are common (they have 2000+ lenses)
- many see UV light, or have better vision than humans
- crustaceans and insects can taste
- special hairs are used for sensing
- ears often in odd places
- various defense mechanisms
11
Q
how do arthropods move
A
- muscles generate force to exoskeleton
- move at joints
12
Q
how do arthropods reproduce
A
- male and females produce eggs and sperm
- internal fertilization
13
Q
how do arthropods grow and develop
A
- exoskeleton inhibits growth
- they must molt, by shedding the exoskeleton, to grow
- in molting the epidermis ingests the inner layer of the exoskeleton and a new soft one is formed, the body pulls out of the shell and inflates before the new one solidifies
- arthropods often undergo metamorphosis to change form
- incomplete metamorphosis involves babies looking like adults as they grow
- complete metamorphosis involves larva that are very different, they grow and become a pupa, where they completely change form
14
Q
what is sub-phyla chelicerata
A
- sub-phyla chelicerata
- spiders, horseshoe crabs, ticks, scorpions, etc
- all have 2 part body and mouth parts called chelicerae
- also lack sensory feelers near head
- 2 body parts: cephalothorax and abdomen
- cephalothorax contains brain, eyes, mouth, mouth parts, esophagus, front of digestive system and some legs
- Abdomen contains most internal organs
- all chelicerates have 2 pairs of mouth parts near the mouth, the first is called chelicerae and the second is pedipalps, differ between groups
15
Q
what are horseshoe crabs
A
- not crabs
- appeared in ordovician (430+ million years ago)
- 5 pairs of legs and long spike like tail
- larva are called trilobite larva as they look like trilobites
- grow from 1cm at hatching up to 60 cm0
16
Q
what are arachnids
A
- spiders, scorpions, ticks, mites
- 4 pairs of legs on cephalothorax
- many are carnivores with pedipalps adapted to hold prey and chelicerae used to bite and suck prey
17
Q
what are spiders
A
- carnivores, small prey like insects or small vertebrates
- may use webs or dents to ambush prey
- chelicerae inject venom
- enzymes break down tissue, turning it into soup while it is sucked up
- produce a protein called silk with gland in the abdomen, six times stronger than steel
- use spinnerets to make webs and structures
18
Q
what are mites and ticks
A
- parasites , very small
- chelicerae are needle like and pierce host
- pedipalps may have claws to attach to host
- cause many diseases and problems
19
Q
what are scorpions
A
- warm weather carnivores, small invertebrates
- pedipalps are claws
- have stinging barbs on abdomen
- chews prey using chelicerae
20
Q
what is sub-phyla Crustacea
A
- subphyla crustacea
- 35000+ species
- mainly aquatic
- vary in size
21
Q
what is subphyla uniramia
A
- so many species, more than any other group
- subphyla uniramia
- centipedes, millipedes, insects
- have one pair of antennae and no branching appendages
- evolved on land 400+ million years ago
22
Q
what is the form of crustaceans
A
- have hard exoskeleton, 2 pairs of antennae and mouth parts called mandibles
- have head, thorax and abdomen, or cephalothorax + abdomen
- a tough shell called the carapace may cover the cephalothorax
- may have CaCO3 in exoskeleton to make hard shells
- antennae are used as sensory feelers or in some cases for filter feeding or as oars
- mandibles can be short heavy structures that bite and grind food
- mandibles can be bristles might be used for filter or detritus feeding
- needlelike mandibles are used to drink blood
- other appendages vary a lot but can include claws, legs, paddles, feathery feelers, powerful tails, etc
23
Q
what are centipedes and millipedes
A
- many legs
- long, worm like, many segments and legs
- around 3000 centipedes
- around 7500 millipedes
- live in moist areas
24
Q
what are centipedes
A
- carnivores, a pair of poisonous claes near the mouth are used to hunt
- eat arthropods. worms, frogs, small snakes, mice, etc
- biggest are around 26cm long
- 15-170 pairs of legs
- most segments have legs
25
what are millipedes
- twice as many legs as centipedes
- 2 pairs of legs per segment
- eat dead plats
- hide and use chemicals for defense
26
what are insects
- 900 000+ species
- vary greatly
- have a head, thorax, and abdomen, 3 pairs of legs
- typically have one pair of antennae, eyes, and 4 wings
- vary a lot in functioning
27
how do insects feed
- 3 pairs of mouth parts including mandibles
- vary in use from cutting, chewing, to sucking
- some pairs have fused together
- saliva may have digestive enzymes or other chemical elements
- other structures like hairs on bees help collect food
28
how do insects move
- 6 legs
- may have spines or hooks
- can be used to jump, hold prey, etc
- can fly, wings on thorax, big muscles along with mitochondria
- may have special blood supply to wings
29
what are insect societies
- some form societies, ex ants, wasps, bees (social insects)
- can be between 6 individuals to 7 million or more
- division of labor is displayed with classes that have different forms
- the basic classes are: reproductive females, reproductive males, and workers
- the reproductive females are called queens and lay eggs, can be 10x larger than workers, have enlarged reproductive organs, usually only 1 but can have more
- the reproductive males fertilize eggs and usually die soon after
- the workers do all the other tasks, gathering food, defending the colony, building, etc
- in ants and termites they specialize to a task
30
how do insects communicate
- sound, visual, chemical, others
- sound examples include chirps, cicada buzzes
- visual example include fire fly light
- chemical examples include pheromones that affect behavior or reproduction of the same species
- pheromones are crucial for insect societies they can be used to signal many things or change development of a queen or egg laying individual
- honey bees dance to signal:
- the round dance indicates food has been found within 50m
- the waggle dance indicates food has been found more than 50 m away
- many others
31
how do arthropods fit into our world
- many roles in food chains
- pollination
- symbiosis with ants and acacia tree, cleaner shrimp, etc
- microscopic ticks cover our skin
- help or damage crops
- food
- provide chemicals
- damage life stock and crops
- mosquitoes and others are vectors for disease
- termites destroy structures
