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Organisms 2 > Lecture 19 > Flashcards

Lecture 19 Flashcards

1
Q

Amniotes caracteristics

A

Monophyletic group within vertebrata

Includes
Nonavian reptiles
Birds
mammals

Amniotic membrane around the embryo

Lack gilled larvae

Internal fertilization

Lay eggs on land or retained within the mother

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2
Q

Anamniotes

A

Vertebrates that lacks an amniotic membrane

Informal group that includes fishes and amphibians

Tend to lay their eggs in water

Smaller, slower growing embryos compared to amniotic egg of same size

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3
Q

Eggs in water or on land?

A

In general
Amniotic egg is a “terrestrial egg”
Anamniotic egg is an “aquatic egg”

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4
Q

Adaptations of Amniotes (7)

A 
1 Amniotic egg
2 Thicker and more waterproof skin
3 Rib ventilation of the lungs
4 Stronger jaws
5 High-pressure cardiovascular systems
6 Water-conserving nitrogen excretion
7 Expanded brain and sensory organs
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5
Q

Amniotic Egg parts

A 
The amniotic egg has four extraembryonic membranes:
Amnion
Chorion
Allantois
Yolk sac
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6
Q

Amnion

A

Part of amniotic egg
encloses embryo in fluid (aqueous medium for growth)
cushions embryo

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7
Q

Chorion

A

Part of amniotic egg
surrounds the entire egg and is highly vascularized
Participates in gas exchange (02 in, C02 out)
In most mammals, it contributes to the placenta

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8
Q

Allantois

A

Part of amniotic egg
Participates in gas exchange and stores metabolic waste (uric acid) in birds and nonavian reptiles
Role in development of the placenta in most mammals

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9
Q

Yolk sac

A

Part of amniotic egg
Also found in anamniotes (tends to be larger in amniotes)
Stores nutrients
In marsupials and placental mammals the yolk sac doesn’t store yolk, but contributes to the placenta

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10
Q

Shell of amniotic eggs

A

Many amniotic eggs have a shell (e.g. reptiles, birds)
Eggs of some lizards, some snakes, and most mammals lack a shell

Shell is mineralized, but often flexible

Provides mechanical support

Semipermeable barrier
Allows passage of gases but limited water loss (especially in birds)

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11
Q

Waterproof Skin for amniotes vs amphibians

A

Amphibians
thin, moist skin to permit effective gas exchange
Vulnerable to dehydration and physical trauma (on land)

Amniotes
Change is skin morphology
Thicker, tougher, more waterproof
Few use skin for respiration
protected by hair, feathers, scales
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12
Q

Rib Ventilation of the Lungs for amniotes

A

Amniotes have better developed lungs than amphibians
Reflects an increase in metabolic demands and a reduced ability to breathe through skin

Amphibians use positive ventilation breathing
amphibians push air from oral and pharyngeal cavity into lungs

Amniotes use negative ventilation breathing
expand thoracic cavity to pull air into lungs

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13
Q

Stronger Jaws amniotes

A

Tetrapods have tongue and strong jaw
Amphibians and some reptiles have teeth but don’t chew (swallow prey whole)
Mammals have strong jaw adapted for mastication (chewing)

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14
Q

High-pressure Cardiovascular System amniotes

A

Adaptive for terrestrial organisms
Higher metabolic needs
Heart must pump blood ‘uphill’ (i.e. counteract gravity)

Heart is segmented – more on this later
Fish: two-chambered (1 atrium and 1 ventricle)
Amphibians & most nonavian reptiles: three-chambered (2 atria, 1 ventricle)
Birds & mammals: four-chambered (2 atria, 2 ventricles)

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15
Q

Water-conserving Nitrogen Excretion amniotes

A

most Aquatic organisms - ammonia
Toxic at relatively low concentrations – must be diluted with water (not adaptive for dry terrestrial environments)

Mammals - urea
Concentrated in the kidneys, reduces water loss

Birds and nonavian reptiles - concentrated uric acid
Bladder receives dilute urine
Water and many salts are resorbed in the bladder
Voided as a semi-solid mass of uric acid

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16
Q

Expanded Brain and Sensory Organs amniotes

A

All amniotes have a relatively large brain
Particularly birds and mammals

Better integration of sensory information

Better control of muscles during locomotion

17
Q

Reptile Taxonomy

A

A modern definition of Reptilia*
includes ‘nonavian reptiles’ (as listed above) and birds
Crocodilians
Also includes the extinct dinosaurs

(birds also belong to a clade within Reptilia called Archosauria)

18
Q

Class Reptilia orders

A

Order Testudines
-Turtles

Superorder Lepidosauria

  • Tuataras
  • Squamata (lizards, monitors, snakes)

Archosauria (no rank)

  • Crocodilians
  • Birds
19
Q

General Characteristics: Non-Avian Reptiles

A

Ectothermic

Tetrapods
Two paired limbs
However, limbs vestigial or absent in many

Body covered in keratinized epidermal scales

Usually dioceious
Some lizards reproduce by parthenogenesis

Parental care typically absent
Except in crocodilians

No larval stage

20
Q

keratin in animals

A

Hagfish and Lampreys: keratinized plates for rasping, chewing

Tadpole has keratinized jaws for scraping vegetation

Non-avian reptiles: body is covered with keratinized epidermal scales

Outer layer of turtle shell is covered in keratin

21
Q

What is keratin?

A

Fibrous structural protein

Very tough material

Found in reptiles, amphibians and mammals
Hair, horns, nails, claws, hooves, scales, shells, feathers, beaks, quills

Analogous function to chitin

22
Q

Testudines - Turtles

A

Enclosed in shell
Dorsal carapace
Ventral plastron (breastplate)

Outer layer composed of keratin

Inner layer composed of bone

Bony layer is a fusion of ribs, vertebrae and other bone

Unique among vertebrates – turtle limbs are located inside the ribs

23
Q

Testunides - Reproduction

A

Oviparous

Internal fertilization

All turtles (even marine) bury shelled, amniotic eggs in the ground

Once nest is constructed, it is abandoned

24
Q

Lepidosauria

A

Squamata
lizards,
monitors,
snakes

Tuatara
lizard-like animals
endemic to New Zealand

25
Q

Kinetic skull

A

Squamata have them

Skull specializations for swallowing large prey

Snake skulls even more kinetic than lizards

Major factor that enabling diversification of snakes and lizards

26
Q

Lizards characteristics

A

A paraphyletic group

familiar animals such as geckos, iguanas, skinks, monitors (e.g. Komodo dragon), chameleons

Most have four limbs
A few (e.g. glass lizard) are completely limbless

Moveable eyelids

27
Q

Lizards temperature

A

Ectothermic (like nearly all nonavian reptiles)
Adjust body temperature by moving among different microclimates

Few species in cold climates
few opportunities to warm up

successful in warm climates with low productivity (e.g. tropical deserts)
Because of the energy savings associated with being ectothermic

28
Q

Snakes characteristics

A

Monophyletic group

Limbless

Vertebrae are shorter, wider, and more numerous than other tetrapods

Differ from lizards in several ways:
No moveable eyelids (snakes eyes covered by a translucent cap)
No external ear openings
Internal ears only hear sounds in a limited range of low frequency
Skull even more kinetic than lizard skull (larger range of motion)

29
Q

Snakes vs Lizards?

A

What is the difference between a limbless lizard and a snake?
Different common ancestor!
Lizards have moveable eyelids…snakes don’t
Lizards have ear openings…snakes don’t
Snake skull is more kinetic

30
Q

Snakes – Capturing Prey

A

Kinetic skull
Skull bones are loosely articulated
Two halves of the lower jar are joined only by muscle and skin

Jaws have posterior facing teeth that anchor prey and slowly move it in

Snakes can swallow very large prey (several times their own diameter)

How do they breathe?
Tracheal opening is extended forward between the mandibles

31
Q

Snakes - smell

A

All snakes and some lizards use their tongues for smell

Employ Jacobson’s organs
Paired organs located in roof of mouth
Line with olfactory epithelium

Forked tongue flicks through air collecting scent molecules

Draws past Jacobson’s organs

Also have olfactory areas in the nose (less well-developed)

32
Q

Tuataras

A

Lizardlike animal

Endemic to New Zealand
2 living species
Sole survivors of a lineage that diverged from Lizards and Snakes

Endangered species
Threatened by non-native species (e.g. cats, dogs, rats, goats)
Slow reproduction rate – 
10-20 years to reach sexual maturity
Produce eggs once every 4 years
33
Q

Crocodilians characteristics

A

Order Crocodilia: alligators and crocodiles
more closely related to birds than other non-avian reptiles

Elongated, robust, well-reinforced skull and massive jaw musculature

Wide gape and powerful closure

Teeth are replaced (like sharks)

34
Q

Alligator vs Crocodile

A

Alligator head and jaws are wider and shorter than crocodile

Alligators teeth are less visible with mouth closed

35
Q

Crocodilians - Reproduction

A

Oviparous

Female lays 20-50 eggs and buries them in sand

Extensive parental care:
female guards eggs
opens nest when hears vocalizations of the hatchlings
Young are guarded by mother for 2 years after hatching

Incubation temperature determines the sex ratio of the offspring
Low nest temperature produces only females
High nest temperature produces only males
Opposite pattern from turtles (high temp = female, low temp =male)

36
Q

Temperature-dependent sex determination (TSD)

A

Genetic sex determination in most snakes and lizards, and some turtles
Z/Z = male, Z/W = female
Same system used in birds

Temperature-dependent sex determination (no sex chromosomes) in all crocodilians, most turtles, and some lizards and snakes

Organisms 2 (23 decks)

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