Adaptations of the Platypus adam Ohl

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Adaptations of the Platypusadam Ohl
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Question

• What types of adaptations has the platypus
  evolved what purpose do these adaptations serve?
• Focus on Appendages, Venom, and Sensory
  Adaptations.

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Lineage

• Synapsids- Mammals, and mammal like animals.
• Monotremes- Egg laying mammals.
• Only found in Australia
• Platypus and Echidna

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• Steropodon
• Cretaceous period 65-146 MYA

• Obdurodon
• 5-25MYA
• larger beak and body then platypus

• Little is known about platypus ancestry.
• Earliest known platypus fossil is about 100,000
  years old.

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Present day Platypus
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Appendages/Swimming mechanism

• Four webbed feet
• Front feet have retractable webbing for land use
• Front feet are used for to paddle through water
• Hind feet are used for stabilization.
• Beaver like tail
• Used as a rudder
• Video

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• Feet on land
• Very clumsy walkers
• Walk as reptiles with feet to the sides
• Frontal feet
• Used for digging
• Hind feet
• Used for anchoring

• Why did they evolve these mechanisms?
• Believed that as ancestors began to depend on
  food sources from water they less relied on land
  sources
• Proven by platypuses ability to move on land.
• Ancestors such as Steropodon had feet with little
  webbing and were probably more home on land near
  water then actually in the water.

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Venom

• Only males can produce venom
• Venom is strong enough to kill smaller animals,
  and can cause sever pain and disable a person.
• Males spurs are grow larger in mating season.
• Meant for male to male competition.
• Spatial Segregation.

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Senses

• Eyes and Ears an Nose
• Small eyes and ears and nose
• Eyes, ears, nose are closed when diving.

If Platypuses spend the majority of their time in
water or in underground nests then why do they
retain these attributes at all?
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• Believed that ancestors who used to live on land
  but dive in water actually used their outward
  senses. Traits of eyes and ears were passed on
  though the uses of them were diminished
• If platypus does not rely on outward senses then
  what do they use?

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The Bill!!!!!

• Hundreds of thousands of tiny electroreceptor's
  and mechanoreceptors.
• Located on Dorsal side of beak
• Detects water disturbances and electrical
  discharges.
• Possibly developed during Cretaceous- Tertiary
  extinction event.
• Roughly 65 million years ago.

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Mechanoreceptors- Detect physical disturbances
in the environment Electroreceptor's- detect
electrical discharge from muscle contractions of
other organisms.
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Ideas of New research

• Study of genetic make up to create a defined
  ancestor lineage.
• I would like to know more about the significance
  of the why the platypus continues to lay eggs.

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Gregory, J., Iggo, A., Mcintyre, A., and Proske,
U. 1988. Receptors in the Bill of the Platypus.
Journal of Physiology 400 349-366.   Pasitschniak
-Arts, M., and L. Marinelli. 1998.
Ornithorhynchus anatinus. Mammalian Species 585
1-9.   Pettigrew, J., P. Manger., and S. Fine.
1998. The sensory world of the platypus. The
Royal Society 353 1199-1210.   PLATER, G., R.
Martin., and P. Milburn. 1995. A Pharmacological
and Biochemical Investigation of the Venom from
the Platypus (ORNZTHORHYNCHUS ANATZNUS).
Toxicon.33 157-169.