chemical defence - marine...
TRANSCRIPT
nonmetals
1
H1.01
Hydrogen
2
He4.00Helium
3
Li6.94Lithium
11
Na22.99Soduim
19
K39.10
Potassium
37
Rb85.47Rubidium
55
Cs132.91Caesuim
87
Fr(223)
Francium
4
Be9.01
Beryllium
12
Mg24.31
Magnesium
5
B10.81Boron
13
Al26.98
Aluminum
6
C12.01Carbon
14
Si28.09Silicon
7
N14.01Nitrogen
15
P30.97
Phosphorus
8
O16.00Oxygen
16
S32.07Sulpher
9
F19.00Fluorine
17
Cl35.45Chlorine
9
Ne20.18
Neon
18
Ar39.95Argon
20
Ca40.08Calcium
38
Sr87.62Strontium
56
Ba137.33
Barium
88
Ra226.03
Radium
105
Db(262)Dubnium
22
Ti47.88Titanium
40
Zr91.22
Zirconium
72
Hf178.49Hafnium
57
La138.91Lanthanum
89
Ac227.03Actinium
58
Ce140.12
Cerium
60
Nd144.24
Neodymium
92
U238.03Uranium
61
Pm(145)
Promethium
93
Np237.05Neptunium
62
Sm150.4
Samarium
94
Pu(244)
Plutonium
63
Eu151.96Europium
95
Am(243)
Americum
64
Gd157.25Gadolinium
96
Cm(247)Curium
65
Tb158.93Terbium
103
Lr(260)
Lawrencium
66
Dy162.50
Dysprosium
97
Bk(247)
Berkelium
67
Ho164.93Holmium
98
Cf(251)
Californium
68
Er167.26
Erbium
99
Es(252)
Einstienium
69
Tm168.93Thulium
100
Fm(257)Fermium
70
Yb173.04Ytterbium
101
Md(258)
Mendelevium
71
Lu174.97Lutetium
102
No(259)
Nobelium
90
Th232.04Thorium
59
Pr140.91
Praseodymium
91
Pa231.04
Protactinium
23
V50.94
Vanadium
41
Nb92.91Niobium
73
Ta180.94Tantalum
106
Sg(263)
Seaborgium
24
Cr52.00
Chromium
42
Mo95.94
Molybdenum
74
W183.85Tungsten
107
Bh(262)Bohrium
25
Mn54.95
Manganese
43
Tc(98)
Technetium
75
Re186.21Rhenium
108
Hs(265)Hassium
26
Fe55.85
Iron
44
Ru101.87Ruthenium
76
Os190.23Osmium
109
Mt(266)
Meitnerium
27
Co58.93Cobalt
45
Rh102.91Rhodium
77
Ir192.22
Iridium
110
(269)
111
(272)
112
(277)
114
(281)
116
(289)
118
(293)
28
Ni58.70Nickel
46
Pd106.4
Palladium
78
Pt195.08Platinum
29
Cu63.55Copper
47
Ag107.87
Silver
79
Au196.97
Gold
30
Zn65.39
Zinc
48
Cd112.41Cadmium
80
Hg200.59Mercury
31
Ga69.72Gallium
49
In114.82
Indium
81
Tl204.38Thallium
32
Ge72.61
Germanium
50
Sn118.71
Tin
82
Pb207.2
Lead
33
As74.92Arsenic
51
Sb121.74Antimony
83
Bi208.98Bismuth
34
Se78.96Selenium
52
Te127.60Tellurium
84
Po(209)
Polonium
35
Br79.90Bromine
53
I126.90
Iodine
85
At(210)Astatine
36
Kr83.80Krypton
54
Xe131.29
Xenon
86
Rn(222)Radon
104
Rf(261)
Rutherfordium
21
Sc44.96
Scandium
39
Y88.91Yttrium
Lanthanideseries
(see below)
Actinideseries
(see below)
transition metals
Period1
alkalimetals
IA
rare earth elements – Lanthanideseries
Actinideseries
noble gasses
O
alkaline earth
metalsIIA IIIA IVA VA VIA VIIA
IIIB IVB VB VIB VIIB VIII IB IB
Period2
Period3
Period4
Period5
Period6
Period7
CHEMICAL DEFENCE
Borrowing some one else’s defence
Armed and dangerous
The stayput stonefish
Photo: Larisa Vanstien
What’s in venom?Photo: Clay Bryce
Anemonefish have a ‘symbiotic’ or mutually beneficial relationship with anemones – they use the anemone for protection against predators and in return keep away intruders and keep the anemone free from parasites. Anemonefish can survive amongst the anemone’s stinging tentacles – which paralyse other fish – by producing a mucous that helps to resist the anemone’s venom. Then over a period of time, which can be several minutes to a few hours, the fish performs a ‘dance’ that involves more and more contact with the anemone, until it becomes immune to the stings.
Venom consists of a mixture of proteins that play with critical bodily funtions (such as blood pressure, heartbeat, nerve and muscle activity, and blood clotting), and can cause pain, blisters, fever, convulsions, breathing difficulties and even death in humans. For example, stingray venom contains enzymes which breakdown and kill cells, as well as the neurotransmitter serotonin, which causes muscle contractions. Should you be unlucky enough to be stung by a venomous fish, immerse or wash the sting area in hot water to ‘denature’ (break down) the proteins and seek medical assistance.
You are what you eat
Photo: Larisa Vanstien
With the existence of many predators in the environment, aquatic animals have developed an amazing variety of defence mechanisms. These include hard exteriors, disguise and camouflage, schooling behaviour, hiding or escaping, and body shapes that are difficult to attack. Spines and barbs are also very common, and many species have taken this form of protection one step further by including venom within the spines – making chemical defence another safeguard against attack.
Venom versus poison
Sleep tight
Photo: Aengus Moran
Going off like a neutron bombBoxfish are also known as ‘Neutron Bomb’ fish. This fish usually goes about its business undisturbed by predators because of its bright colours, which act as a warning, and its scales that have developed into an extremely rigid armour. But if those defences fail, the boxfish secretes a toxin through its pores that can wipe out anything in close proximity to it. To protect itself from its own toxin, the boxfish releases the toxin as it quickly leaves the area.
Biting off more than you can chew
Photo: Henrique Kwong
Most ‘nudibranchs’ or sea slugs have the remarkable ability to absorb the toxins and ‘nematocysts’ (stinging cells) of their prey and transfer them harmlessly to the tips of their own tentacles. These assimilated poisons and ‘harpoons’ are then used to defend the nudibranch from its own predators. This is why many sea slugs are so brightly coloured – a warning that they are unsafe to eat.
Pufferfish have a surprise for predators – they can inflate themselves to a size that is too big to swallow. On top of this, they produce a highly lethal toxin called ‘tetrodotoxin’ – present in the fishes’ skin, flesh and internal organs – that is approximately 1,200 times deadlier than cyanide! Pets have died from eating blowfish (a type of pufferfish) washed up on beaches or left behind by fishers.
If a stingray’s ‘barb’ gets broken off as it defends itself, the stingray’s will grow a new one.
A master of disguise, the stone fish is a very inactive predator – lying still on the bottom, looking like an algae-covered rock, waiting to gulp prey into its huge mouth. But if disturbed, frightened or provoked, it will erect the spines along its back to jab enemies with what is the most deadly venom of any fish in the world! Stonefish have control over whether to shoot its venom, unlike other species (such as the lionfish) that can’t release venom unless something pushes against their spines.
Stone fish venom delivery mechanism: A protective sheath blocks the opening. As pressure is applied, the venom seal breaks and a spine is bared. The sheath is punctured, freeing the opening, and the venom is released. The gland is destroyed by the pressure, but will regenerate and be recharged with venom within a couple of weeks.
SpineVenom gland
Protective Sheath
Blocked gland Pressure from victim
Pressure from victim
Pressure from victim
Destroyed gland and crushed sheath
Opening
Gland clear
Crushed sheath
Discharged venom
Venom duct
Compressed venom gland
Venomous fish (such as scorpionfish, stonefish, stingrays and cobbler) deliver their venom by means of a bite or sting, often through injection. Venom is typically produced in organs specialised for the purpose.
Poisonous fish (such as pufferfish and boxfish) are harmful when eaten or touched, with the poison usually absorbed internally or via the skin. The poison tends to be distributed over a large part of the body of the fish producing it.
Toxins describe a biologically-produced poison or venom, that is, the harmful substance is produced by the living cells of the organism.
Fish have a keen sense of smell and can detect minute changes in water chemistry. Some members of the parrotfish family secrete a mucous ‘cocoon’ around themselves when they rest or sleep. This cocoon acts as a chemical shield, masking any scent that they give off and preventing predators like moray eels from finding the parrotfish by smell. Baldchin groper are thought to use this same defence mechanism.
Close behind the stonefish in ‘poison-power’ is the lionfish (also called butterfly cod, fire cod or red firefish), with its long, colourful, fins and fin spines. This decoration may be used for camouflage or possibly to advertise the lionfish’s deadly poison, which is injected by the spines. The toxin is based upon the lionfish’s diet, much in the same way as nudibranchs use the toxic compounds produced by their prey as part of their own defence.
Photo: Sandy Clarke
There have been anecdotal reports of osteoarthritis sufferers experiencing improved mobility and reduction in joint pain following ‘envenomation’ from stonefish. The responsible agent has not yet been identified.
Some anemones release a chemical ‘perfume’ to attract anemonefish to them.
In Japan, fish from the family Tetraodontidae (which includes well over 100 species of toadfish and pufferfish) are known as ‘fugu’ and are considered a delicacy. Young chefs spend years learning how to prepare fugu. However, each year, a few people still die from eating poorly-prepared fugu dishes.
Perfume