L01 - Lizards Flashcards
1
Q
How many body cavities do lizards have?
A
- only have 1 body cavity
- known as celomic cavity
- do not have diaphragm
2
Q
What is lizards structure like?
A
- very mobile
- have a flexible backbone
- long tail for counterbalance
3
Q
Describe the structure of their backbone and vertebrae?
A
- backbone is divided into pre-sacral, sacral and caudal region
- all vertebrae except cervical ones have paired ribs
4
Q
What is the structure of their skull?
A
- more rigid than a snake skull
- have quad ratebone which has no firm attachment, allows forward and backward movement and gives advantage when biting prey
- skull articulates with cervical vertebrae with a single occipital condyle
5
Q
What is their dentition?
A
- lizards have 4 rows of teeth, 1 to each jaw
- there are no fangs
6
Q
What is the structure of their teeth?
A
- teeth are peg like in shape and are continually replaced
- some have hallow teeth allowing venom to ooze through them
7
Q
What is their axial skeleton?
A
- coccygeal vertebrae have ventral haemal arches
- tail has fracture plans and no bone
8
Q
What is autotomy?
A
- this is the spontaneous dropping of the tail
- occurs in lizards except chameleons and monitors
- coccygeal vertebrae are not replaced
9
Q
What is the pectoral girdle made up of?
A
- scapula
- coracoid
- clavicle
10
Q
What is the forelimb made up of?
A
- humerus
- radius
- ulna
- carpal bones
- phalanges/digits
11
Q
What is the pelvic girdle made up of?
A
- ilium
- ischium
- pubis
12
Q
What is the hindlimb made up of?
A
- femur
- tibia fibula
- tarsal bones
- phalanges/digits
13
Q
What limb adaptions have occurred in geckos?
A
- their foot has a sub digital adhesive lamellae, this allows them to cling to walls
14
Q
What limb adaptions have occurred in burrowing lizards?
A
- they have lost their limbs, but still have pectoral and pelvic girdle
15
Q
What limb adaptions have occurred in lizards?
A
- they can hold their forelegs off the ground and run on their hind limbs in a bipedal motion
16
Q
What is metabolic bones disease, and what causes it?
A
- a lack of vitamin D in the diet
- causes weakness and brittle bones
- normally caused by a lack of UV light or calcium deficiency in the diet
17
Q
What are the uses of the respiratory system?
A
- breathing
- threat and display
- buoyancy
- escaping predators
- vocalisation
18
Q
What type of nares do they have?
A
- paired nostrils
19
Q
What is the structure of the trachea?
A
- protected by ruminant larynx
- incomplete c shaped rings of cartilage
- trachea bifurcates into 2 main bronchi, supplying both lungs
- no epiglottis
- often no vocal cords
20
Q
What are the lungs often used for?
A
- defence mechanism
- 2 lungs
21
Q
Describe the process of inspiration?
A
- contraction of intercostal muscles plus elastic tissue
22
Q
Describe the process of expiration?
A
- contraction of intercostal and abdominal muscles plus the elastic recoil of the lung tissue
23
Q
3 key features of their digestive tract?
A
- simple in insectivores and omnivores
- swallowing of stones to aid in digestion is normal in lizards
- geckos use tails as storage device for fats, their emergency supply
24
Q
Describe the structure of their tongue and taste buds?
A
- most have a large fleshy tongue
- tongue is generally mobile and protrusible
- very poorly developed taste buds
25
Describe the structure of their stomach?
- located on left side of their abdomen
- simple, elongated and sac like
- contains glands that secrete hydrochloric acid, pepsin and mucus
26
Describe the structure of their small intestine?
- well developed in carnivorous and insectivorous species
- intestinal tract of herbivores is shorter
- some contain caecum
- caecum present at junction between large and small intestine
27
Describe the structure of their large intestine?
- well developed in herbivorous species
- sacculated, so is divided into chambers by leaf like membrane
- increased surface area allows colonisation by bacterial microbes which help digest plant matter
28
Describe the structure of the cloaca?
- large intestines empty into the cloaca
- this has 3 chambers
- coprodeum, urodeum and proctodeum
- all waste is excreted via the vent
29
Describe the roles of the chambers of the cloaca?
Coprodeum - receives faeces
Urodeum - contains urinary and reproductive tracts
Proctodeum - collecting area for digestive and excretory wastes
30
Describe the structure of the heart, and its role?
- paired atria and single ventricle that acts as 2
- channels deoxygenated blood to the pulmonary arteries
- oxygenated blood to the aortas
31
What 2 cardiovascular systems do lizards have?
- hepatoportal venous supply
- renal portal system
32
Describe the structure of the urogenital system?
- position of the kidneys is variable
- most have a thinned wall bladder
- some do nor have bladders and the urine is stored in the distal colon
- short ureter drains into the urodeum, urine flows into the coprodeum
33
How does colour change occur in lizards?
- they have pigmented cells in the dermis
- connected to neural networks
- dispersion by hormonal or nervous signals enables change of colour according to mood or external stimuli
34
Describe the structure of lizards hearing system?
- eardrum (tympanic membrane) is visible
- covered by thick skin or in some lizards scaly skin
- middle ear is present too
35
Describe the structure of their sight system?
- varies from poor to good
- eyelids are usually present
- parietal eye (third eye)
36
Describe the structure of the parietal eye?
- associated with pineal gland
- well developed, and has lens and retina
37
What does the parietal eye do?
- regulates circadian rhythms
- is light sensitive
- for hormone production and thermoregulation
38
What organ do lizards have for smell?
- Jacobsen’s organ
39
How can gender be determined in lizards?
- males are often brighter coloured and ornamented (horn)
- male geckos and iguanas have femoral pores
- males have a bulge where hemipenes are located, a wider base tail
- can sometimes use a probe
40
Frilled lizards defence mechanism?
- extends neck frills to warn off predators or intruding males
41
Flying lizards defence mechanism?
- facing off another male, bobbing head and showing dewlap
42
Regal horned lizard defence mechanism?
- squirts blood form their eyes in defence
43
Chuckwallas and other lizards defence mechanism?
- overinflate the lungs in attempt to look bigger
