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Biol 448: Final > Cephalopods > Flashcards

Cephalopods Flashcards

1
Q

In what way are cephalopods record breakers?

A
  • they are the smartest, largest and fastest
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2
Q

What are the general body features of molluscs?

A
  • radulla: teeth used to scrape or drill holes
  • mantle: covers body and produces shell
  • foot to move
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3
Q

What are the general body features of cephalopods?

A
  • modified foot: arms and funnel

- mouth with a beak

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4
Q

What are the key features of the nautilus shell?

A
  • chambers added as they grow
  • chambers allow for buoyancy to be altered and to maintain upright position
  • counter-shading for camoflage
  • siphuncle perforations through the septa
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5
Q

What are the different types of tentacles that the nautilus has?

A
  • digital tentacles: anchor
  • lateral tentacles: grope around
  • median tentacles to move food to mouth
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6
Q

How is sensitivity increased in the tentacles of the nautilus?

A
  • increased surface area with lamella (ridges) and ciliary fields
  • the cilia for mechanosensory are shorter
  • the cilia for chemosensory are longer
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7
Q

How do the nautilus eyes work?

A
  • pinhole camera
  • light travels through the hole and arrives at a point on the back of the eye which is composed of light sensitive cells
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8
Q

What issues must the nautilus overcome with pinhole eyes?

A
  • if eyes small: focused but dim
  • if eyes large: bright but fuzzy
  • must produce mucus from goblet cells to clear pathogens from the eye (since seawater and sediment gets in)
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9
Q

What study was conducted to examine the visual acuity of nautilus eyes?

A
  • Muntz et al
  • nautilus put in tank surrounded by drum with stripes
  • if the nautilus could perceive the stripes it would turn with the drum to orient itself
  • minimum visual resolution between 5 and 11 degrees (two objects must be more that 5 degrees apart to be perceived)
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10
Q

How do the cephalopods differ in supporting structures?

A
  • nautilus: shells
  • squid: flexible rod
  • octopus: beak
  • cuttlefish: bone
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11
Q

How do the squids use jet propulsion?

A
  • shoot water out funnel

- can aim funnel to direct themselves

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12
Q

What type of circulatory system do squid have?

A
  • closed circulatory system

- supports their active lifestyle

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13
Q

What does not having a shell risk and what is gained?

A
  • higher risk of being eaten

- better manuverability

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14
Q

What tentacles do squid use for predation?

A
  • two long tentacles
  • end called tentacle clubs and contain suckers
  • tentacle stalk
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15
Q

What kind of eyesight do octopuses have?

A
  • lens to focus light
  • lens is moved back and forth to focus light
  • light enters eye and hits the photoreceptors at the back
  • octopuses are able to see polarized light because of microvilli
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16
Q

What is the octopuses organ of equilibrium? What is it used for?

A
  • complex statocytes that are made up of base, macula, and three cristae
  • cristae detect angular acceleration
  • macula detects forward acceleration
  • to gain information about body position and movement
17
Q

What adaptation/abilities do cuttlefish have?

A
  • lateral lines that contain hair cells that detect movement in water
  • useful for avoiding predators
18
Q

What is used for colour changing in cephalopods?

A
  • chromatophores: sacs filled with pigments (black, brown, red, orange, yellow)
  • chromatophores are under nervous system control and are connected to radial muscle fibers
  • reflecting cells: located below chromatophores and three different types (blue and green, iridophores: pink, yellow, green, blue and silver, leucophores: white spots)
  • stellate ganglion relays from brain to change colour pattern
19
Q

What else do octopuses do aside from change their colour for camoflage?

A
  • mimic octopuses change their behaviour to appear like flounders, lion fish, and sea snakes
20
Q

What defense mechanisms do cephalopods have?

A
  • ink jet to produce curtain

- photophores are bioluminescent and may be involved in mating or defense

21
Q

How do cephalopods know which chromatophores to use for counter shading?

A
  • they use temperature
  • warmer in shallow water: green
  • colder in deeper water: blue
22
Q

What is unique about the vampire squid?

A
  • see colour

- live in the deep so only see bioluminescents

23
Q

How do the pacific giant octopus mate?

A
  • female detects fitness level of potential mates with chemosensory
  • if chosen she cracks their sperm packet over her eggs
  • she airates the eggs until they hatch and then she dies
24
Q

What is the relationship between body weight and brain weight in some cephalopods?

A
  • larger brains compared to body weight then fish and reptiles but less than birds and mammals
25
Q

How have cephalopods demonstrated tool use?

A
  • use shells or coconut halves as protection

- able to learn to open jars or solve puzzles

26
Q

What has been observed about octopus memory and learning abilities?

A
  • learn by observation (surprising since solitary)

- can remember: octopus given food in a certain tube, favoured that tube every time after

27
Q

What types of synapses do cephalopods use?

A
  • electrical and chemical, neuro-neuronal and neuromuscular, uni- and bi-directional and en passant
28
Q

What is the general octopus nervous system?

A
  • majority of neurons in arms
  • ganglia with cell bodies on outside and processes on inside
  • brain contains 40 lobes
29
Q

What are two important octopus lobes and what are their functions?

A
  • vertical lobe: useful for learning and memory, contains two types of monopolar neurons (small amacrine and large neurons)
  • median superior frontal lobe: important for integration of sensory info, provides input to vertical lobe with en passant synapses with amacrine cells
30
Q

What are some of the featyres of the vertical lobe?

A
  • 5 cylindrical gyri to increase surface area
  • large number of small neurons
  • folds
  • reminiscent of hippocampus
31
Q

What neurotransmitters have been found in the rai of octopus vulgaris?

A
  • oxytocin/vasopresson-related peptides

- GnRH-like peptide

Biol 448: Final (7 decks)

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