physiology of foraging Flashcards

1
Q

what are the two states of food acquisition

A

finding food and securing food

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2
Q

how can food be located

A

by chance encounter or active hunting

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3
Q

how does the star nosed mole find food

A

an exaggerated touch sense using Eimer’s organs which cover appendages and sense touch through exposed nerve endings, merkel cells and lamellated corpuscles

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4
Q

how do bats use echolocation

A

changes in amplitude/timing between ears is directional. doppler shift detecting change in frequency tells it if the object is moving closer or away

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5
Q

how do bats generate calls

A

contraction of the larynx muscle. it becomes more rapid during buzz phase as it approaches its target

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6
Q

how are bats adapted to hear calls

A

funneled auricles and motor protein prestin which is on the basilar membrane and detects high frequency sound

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7
Q

who uses electrolocation and what does it sense

A

used by sharks and rays. they detect electrical fields generated by muscle contraction of prey

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8
Q

how is electrolocation detected

A

impulses travel through conducting gel- filled canals to stimulate ampulla of Lorenzini (sense organ). impulses are sent straight to the brain

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9
Q

what is IR

A

infrared ratiation with wavelength 700nm-1mm. most thermal radiation is IR

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10
Q

how do pit snakes detect IR

A

innervation of the pit membrane by trigerminal ganglia neurones which are rich in temperature- sensitive TRPA1 ion channels

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11
Q

how do pit snakes visualise IR

A

impulses from TG neurones converge with optic nerve impulses in the optic tectum so they ‘see’ IR

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12
Q

how do vampire bats detect IR

A

similarly to pit snakes with pit organs, however they use a short isoform of TRPA1 (TRPA1S) which is more temperature sensitive

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13
Q

how do vampire bats prevent self detection and why is this necessary

A

their nose (where the 3 pit organs are) is 9 degrees colder than the rest of the face. this is necessary as bats are warm blooded mammals

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14
Q

what are the three mechanisms of securing a meal

A

physical, electrical and chemical

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15
Q

how is spider silk formed

A

it forms micelle- like structures in the sac. a reduced pH in the spinning duct elongates proteins and forms fibres

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16
Q

which form of silk is most valuable in predation

A

swathing silk- around 300 aciniform glands simultaneously form a silk ‘sheet’ to wrap prey

17
Q

what is the structure of electric organs

A

they are filled with stacks of around 5000-6000 electrocyte disks which have two distinct faces

18
Q

how is a potential difference generated in electric organs

A

one face of the disk is depolarised and the other is polarised. the summative potential difference of the organ is around 860V

19
Q

what is the composition of venom

A

it is made up of neurotoxins, enzymes and pore forming toxins

20
Q

what do neurotoxins target

A

fast- acting proteins ie ion channels. these include Na, Ca, K, nAChR and iGluR

21
Q

what are peptide neurotoxins

A

small peptides which have lots of disulfide bridges due to high quantities of Cys residues. they target all types of ion channels

22
Q

which ion channels cause which paralysis in peptide neurotoxins

A

K and Ca cause rigid paralysis, Na, nAChR and iGluR cause flaccid paralysis

23
Q

which ion channels cause which paralysis in non- peptide toxins

A

Na, Ca, nAChR and iGluR all cause flaccid paralysis

24
Q

how is venom stored

A

as pro- venom to prevent self toxicity. it is enzymatically modified at release to become active

25
how is venom usually delivered
by fang, sting or modified leg. they have modified elongated holes/ deep grooves to prevent blockage or venom ducts
26
how do cnidarians deliver venom
toxic harpoons. they are stored inside out in nematocysts and are triggered by cnidocil touching prey
27
how do cone snails paralyse prey
in a two step paralysis- rigid then flaccid. they use toxic harpoon called radula