A presentation on Marine Iguana

1. UNIVERSITY OF LAGOS
FACULTY OF SCIENCE
DEPARTMENT OF MARINE SCIENCES
MSM 439: SEMINAR
TOPIC: MARINE IGUANA
BY
DEMEHIN, GBENGA OLUWAYEMI
130811008
MARCH 23RD, 2017
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2. MARINE IGUANA
(Amblyrhynchus cristatus)
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3. OUTLINE
1.0 INTRODUCTION
2.0 CLASSIFICATION AND DESCRIPTION OF
MARINE IGUANA
3.0 DISTRIBUTION AND HABITAT OF MARINE
IGUANA
4.0 BIOLOGY AND ECOLOGY OF IGUANA
5.0 ADAPTATION OF MARINE IGUANA
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4. 1.0 INTRODUCTION
Marine iguanas are the world’s only sea going lizards.
The marine iguana is scientifically known as
Amblyrhynchus cristatus.
It is an iguana found only on the Galápagos Islands,
and is sometimes called the Galápagos marine iguana.
The iguana can dive over 9metres (30 feet) into the water.
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5. 2.0 CLASSIFICATION AND DESCRIPTION OF
MARINE IGUANA
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Iguania
Family: Iguanidae
Genus: Amblyrhynchus
Species: A. cristatus (Bell, 1825)
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6. Plate 1: Marine Iguana sun bathing on the Santa Cruz island Source: Leyden, 2015.
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7. Description
The marine iguana body is elongate and fusiform.
 The average length of an adult male is approximately 1.3 meters and
an adult female is approximately 0.6 meters in length.
They have a short, blunt nose and snout, a laterally compressed tail.
They have razor-like teeth, long, sharp curved claws and very distinct
jagged crest.
They are either black or dark grey in colour except when males are
near mating seasons when they turn shades of red and green.
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8. Plate 2: Marine Iguana darting across the sand Source: Kovacevic, 2014
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9. 3.0 DISTRIBUTION AND HABITAT
The geographical range of the marine iguana is in the
coastal areas of all of the islands, islets, and sea rocks of
the Galapagos Islands.
The total population has been estimated at between
200,000 and 300,000.
Marine iguanas live in colonies where shallow reefs occur
with an extensive intertidal zone and a rocky coastline
approximately 2 to 5 meters above sea level.
Young iguanas are found among adults. Unlike adults, they
spend are great amount of time in cracks and crevices. They
are never far away from a hiding place.
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10. The Galapagos Islands
Plate 3: The Galapagos islands Source: Operecuador, 2016 Plate 4: Latitudinal Position Source:Worldaltals, 2008
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11. Figure 1. Map of Distribution of Marine iguanas Source: Elisa, 1999
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12. 4.0 BIOLOGY AND ECOLOGY
• DIET
They are herbivorous.
They feed almost exclusively on marine algae.
Only the largest five percent of individuals dive into the
water for food.
The waters are extremely cold, and cause the iguana to lose
heat rapidly when feeding.
Small individuals, which lose heat quickly, forage on rocks at
low tide, scraping algae off the surface, and rarely dive into
the sea.
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13. Plate 5: A marine Iguana feeding on algae Source: Pierce, 2016
They consume a great deal of salt solution when they feed and this can be toxic
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14. Reproduction
This species breeds every year over a three month period, during which
the males defend mating territories.
Individuals breed normally just once every two years.
The nesting months are January through to April depending on the
island.
Females lay between one and six eggs up to 300 meters inland, in sand
or volcanic ash burrows that are 30 to 80 cm deep.
Incubation takes approximately 95 days
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15. Plate 6: A male and a female Marine Iguana Mating Source: Wikelski, 1999
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16. 5.0 ADAPTATION
Marine Iguana consume a great
deal of salt solution as they
feed and this can be very toxic.
Once they are back up on land
they need to get rid of all that
salt.
 They do that with the help of
their salt-excreting glands.
 As they sneeze, out comes the
saltwater. Plate 7: Marine iguana sneezing Source: Wikelski, 1998
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17. They are cold-blooded organisms.
And are therefore restricted by how long they can stay in
the cold ocean waters.
Before feeding, the lizards must raise their body
temperature to about 36°C, as they can lose up to 10°C
when in the ocean.
They must also warm their bodies again following the dive.
Consequently, the dark coloring of the iguanas is critical
to allowing them to absorb sunlight.
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18. PREPARING FOR ANOTHER
DIVE
Plate 8: A colony of Marine Iguanas sunbathing Source: Wikelski, 1999
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19. ADAPTATION CONTD.
The Galapagos Islands are highly affected by El Niño and La Niña
climate fluctuations.
 During extreme El Niño events, the primary food source of the
marine iguanas, algae, becomes severely depleted, disastrously
affecting their population levels.
During these times, the body of the iguana actually shrinks in size,
and then regrows again when food is once more plentiful.
This is the first known reporting of the shrinking of an adult
vertebrate. 19

20. THREATS
• El Niño events cause the greatest mortality in marine
iguanas, with up to 70% dying in some populations in the
great 1982-83 El Niño.
• Oil spills and marine pollution are also very serious threats as
they destroy food reserves and the nesting beaches.
• Recent research has also found high mortality of Galapagos
marine iguanas on Isla Santa Fe resulting from the subtle
long-term effects of the 2001 oil spill from the grounded
tanker Jessica. 20

21. Video: Swim Along side a Galapagos Marine Iguana Source: Swinksworth, 2012.
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22. IUCN RED LIST STATUS
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23. CONCLUSION
The future of this species is unclear. One cause for
concern about the marine iguana is that the human
population of the Galapagos Islands has risen from 4,000
people just 15 years ago to approximately 12,000 people
today. Population pressure on the islands may have
adverse effects for the iguana. Additionally, with the
introduction of more people on the island that will mean
more pets and domestic livestock. Dogs, cats and pigs
have impacted upon the population of marine iguanas.
There is need to strategically control anthropogenic
pressures and introduced feral animals on the Galapagos
islands to sustain this species.
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