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Diversity of Life 2 > Arthropods > Flashcards

Flashcards in Arthropods Deck (46)
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1
Q

Arthropods are protostomes, what does this mean?

A

Their blastopore becomes their mouth, they are bilaterally symmetrical, they have an anterior brain which surrounds the entrance to the digestive tract and have a ventral nervous system with longitudinal paired/fused nerve cords.

2
Q

What are ecdysozoans?

A

Organisms which have exoskeletons secreted by an underlying epidermis.

3
Q

How do ecdysozoans grow?

A

By moulting their exoskeleton and replacing them with a larger one.

4
Q

What is heteronomous metamery?

A

A reduction in metamerism.

5
Q

Give characteristics of the Onychophorans.

A

AKA the velvet worms.

  • Ecdysozoans but not arthropods.
  • Soft, fleshy, claw-bearing and unjointed legs.
  • Thin, flexible, chitinous cuticle.
  • Hydrostatic skeleton.
6
Q

Give characteristics of the Tardigrades.

A
  • Ecdysozoans but not arthropods.
  • Eight fleshy, unjointed legs.
  • Hydrostatic skeletons.
  • Lack a circulatory and gas exchange system.
  • Can survive a decade or more in dormant state.
  • Live on temporary water films of plants.
7
Q

What do arthropods have instead of a coelom?

A

A haemocoel which allows fluid from their open circulatory system to bathe the internal cavities.

8
Q

Give characteristics of the Trilobita.

A
  • Early arthropods.
  • Showed signs of specialisation.
  • Cambrian and Ordovician seas were their habitat before their extinction in the end of the Paleozoic.
  • Heavy exoskeletons.
9
Q

What is chitin?

A

A strong polysaccharide in arthropod exoskeletons. Restricts movement and gas exchange.

10
Q

How do animals with chitinous exoskeletons move?

A

With specialised appendages.

11
Q

What allowed aquatic arthropods to invade the land?

A

Waterproof chitin.

12
Q

Give characteristics of the Myriapods.

A
  • AKA centipedes and millipedes.
  • Centipedes have 1 pair of legs per segment while millipedes have two adjacent segments fused so that there is 2 pairs of legs per segment.
13
Q

Give characteristics of the Chelicerata.

A
  • Bodies divided into two regions.
  • Anterior region has two appendages modified to form mouthparts.
  • Many have 4 pairs of legs.
  • Chelicerate structures include a prosoma, an opisthosoma, no antennae, chelicerae and pedipalps.
14
Q

What are the Pycnogonids?

A

Sea spiders.

15
Q

What are the Xiphosura?

A

Horseshoe crabs.

16
Q

Give characteristics of the Arachnida.

A
  • Spiders, scorpions, mites and ticks.
  • Most have simple life cycles.
  • Others retain their eggs during development and give birth to live young.
  • Mites and ticks are vectors of disease.
17
Q

How do spiders spin webs?

A
  • Webs are used to capture prey.
  • Silk is extruded from spinnerets.
  • Spiders apply pressure and pull the thread while changing it from solid to liquid.
18
Q

How do spiders spin webs?

A
  • Webs are used to capture prey.
  • Silk is extruded from spinnerets.
  • Spiders apply pressure and pull the thread while changing it from solid to liquid.
19
Q

How do spiders spin webs?

A
  • Silk is extruded from spinnerets.

- Spiders add pressure and pull the silk out while changing it from liquid silk to thread.

20
Q

What are the three families of Entognatha?

A
  • Collembola.
  • Diplura.
  • Proturans (wingless relatives of insects).
21
Q

Give characteristics of the Insecta.

A
  • Have three major body regions.
  • Head with a single pair of antennae.
  • Thorax with three pairs of legs.
  • Abdomen with no appendages.
22
Q

What are the two groups of Apterygota?

A
  • Jumping bristletails and silverfish.
23
Q

What are the features of true insects?

A
  • Large compound eyes.
  • Maxillary palps.
  • Multi-segmented antennae.
24
Q

How do apterygota metamorphose?

A
  • Ametabolously. This means they continue to grow and moult through their life.
25
Q

What are the pterygota?

A
  • Insects with wings.
26
Q

What are the two divisions of pterygota and how are they distinguished?

A
  • Paleoptera: those that cannot fold their wings back against their body.
  • Neoptera: those that can.
27
Q

Describe the mayfly life cycle.

A

The majority is spent as a nymph, adult mayflies only live long enough to mate and lay eggs.

28
Q

What are the stages between moults in insects called?

A

Instars.

29
Q

What is incomplete metamorphosis?

A

Happens in hemimetabolous insects. Gradual changing between instars.

30
Q

Give examples of hemimetabolous insects.

A

Grasshoppers, cockroaches, stick insects, termites, earwigs and cicadas.

31
Q

What is complete metamorphosis?

A

Happens in holometabolous insects. Has a larval stage which transforms insect called a pupa.

32
Q

Give examples of holometabolous insects.

A

Butterflies, bees, beetles, lacewings, ants.

33
Q

What are the most basic insect mouthparts?

A

Left and right mandible, left and right maxillary palps, labrum and labium.

34
Q

How are mouthparts modified for fluid feeding?

A

Modification to form a tube to draw liquid in.

Pharynx muscles developed to form a pump.

35
Q

What insects feed on animal and plant fluid?

A

Hemiptera and diptera.

36
Q

What is the difference between male and female mosquitoes?

A

Males feed on plant sap only while females feed also on blood.

37
Q

Describe the mouthparts and feeding technique of mosquitoes.

A

Mosquito mandibles and maxillae are formed into needle like structures enclosed by the labium.
When a mosquito bites, the maxillae pierce the dermal tissue, anchoring the mosquito to the tissue. The labium then slides back and the remaining mouthparts pass through its tip and into the tissue. The mosquito then injects anticoagulants to prevent clotting while pumping blood through the tube with two head muscles.

38
Q

How do bees collect pollen?

A

Pollen collected on head is brushed off with fore and middle legs before passed to hind legs which also collect pollen from abdomen using the comb on the basitarsus. Pollen collects between tibia and basitarsus. Closure of the basitarsus forces pollen into pollen basket.

39
Q

How do flies cling to walls?

A

2 claws and 2-3 pads. Pads contain thousands of tenent hairs with spatula-like tips and have closely associated gland cells which secrete lipoproteins.

40
Q

What is myiasis?

A

When a female oviposits eggs into a host through a bite hole. The larvae then pass through three instars before falling to the ground to pupate.

41
Q

What are blood feeding insects attracted to?

A

Fatty acids, CO2, octanol, ammonia and phenols, heat and vibrations.

42
Q

How do hosts stop excessive bleeding?

A

Platelet aggregation.
Blood coagulation.
Vasoconstriction.

43
Q

What are parasitoids?

A

Remain in contact with host and eventually kill and consume them.

44
Q

What are hyperparasitoids?

A

Parasitoids that attack parasitoids.

45
Q

How do parasitoids locate hosts?

A
  • Semiochemicals.
  • Photosensory cues like landmarks, shapes and colours.
  • Thermosensory cues like IR radiation in some species.
  • Learned cues like a good experience in a location in their lifetime.
46
Q

How do cotesia defend against parasitoids?

A

Permanently suppress encapsulation by carrying a polyDNA virus in ovaries which is released into host when wasp oviposits. This virus includes host tissue, causing them to produce novel proteins.