Tuatara

Question 1

What is the scientific name of the tuatara?

What order do they belong to?

How long do they live?

What is a primary cnservation threat?

How do you sex them?

Where do they live?

What is their behavior like?

Answer 1

Tuatara (Sphenodon punctatus) - unique reptiles endemic to New Zealand

• Only extant members of the order Rhynchocephalia
• Rats considered primary threat as predators of tuatara eggs and juveniles and competitors for food.
• Long lived (80+ years).
• Sexually dimorphic.
  
  • Males larger with larger head than females.
  • Males more prominent nuchal and dorsal crests and spines.
  • Juveniles best sexed via coelioscopy.
• Nocturnal but emerge during day to bask.
• Size varies with geographic location.

Taxonomy

• Superorder Lepidosauria
  
  • Sphenodon punctatus – only recognized species of tuatara

Question 2

What is unique about the dentition of the tuatara?

What reproductive differences exist between tutataras and lizards?

What unique musculoskeletal feature do they have?

What about their thermoregulation?

Answer 2

• Dentition – acrodont
  
  • 2 upper rows of teeth – complete outer row attached to maxilla and shorter inner row attached at lateral edge of palatine bone
  • single lower row of teeth - fits into gap between two upper rows and moves rostrally relative to upper jaw
  • pair of large incisor-like teeth at front of upper jaw, attached to premaxilla
  • teeth are added caudally as the animal grows
• Reproductive system
  
  • Sexual maturity 9-16 yrs, breed into 60’s.
  • Males:
    
    • Paired testes – minimal seasonal size variation but testosterone peaks in mating season.
    • No renal sex segment – unlike squamates.
    • No intromittent organ - copulation via cloacal apposition.
  • Female
    
    • Paired ovaries.
    • Vitellogenesis – protracted, can be spread over several years.
    • Eggs present in oviduct for 6-8 months.
    • Lay eggs every 2-5 years in wild.
    • Weight gain in late gravidity.
    • Temp-dependent sex determination within a narrow range.
      
      • Predominantly females produced at 20C, males at 23C.
    • Incubation - longest of any known reptile (10-16 months).
    • F8:
      
      • Mating occurs in late summer (Jan-Mar).
      • Seasonal variations seen in sex steroids of both sexes.
      • Up to 19 soft-shelled eggs are laid.
• Musculoskeletal system
  
  • skull - diapsid with a fixed quadrate bone
  • possess abdominal ribs (gastralia) - not true ribs but develop within dermis
  • Tail autonomy (less readily than lizards)
• Thermal Physiology and Metabolic Rate
  
  • low metabolic rate compared with other reptiles and relatively high activity level in cold temperatures
    
    • Body temps over 28°C can cause signs of heat stress
  • can undergo short periods of torpor in cold weather

Question 3

Describe the ideal housing for a tuatara

Answer 3

F8: Special housing requirements:

• Housing features critical to the good health of tuatara are listed:
  
  • Minimum of 5 sq meters per adult animal.
  • Porous soil substrate to allow for natural burrow construction and egg laying.
  • Adequate insulation of artificial burrows to protect from excessive heat, cold, and moisture.
  • A variety of low-growing shrubs, rocks, hollow logs, and other cage furniture.
  • Ambient temperature of 4-15C in winter, 10-25C in summer, with the animals having a choice of thermal gradients.
  • Relative humidity maintained within 85-95%.
  • Basking opportunities providing 100-250 microwatts per square centimeter of UVB, lower exposure in winter and higher in summer, and warmth for two hours in the morning and afternoon.
  • Open ponds to enable soaking in shallow water, stimulates defecation and prevents dysecdysis in annual molt.

MARMS Ch 26 - Tuatara

Housing

• Cold adapted
• Temps should not be above 25 deg C (77 deg F) or below 4 deg C (39 deg F)
• Recommended winter temp: 4-15 deg C; 10-25 deg C in summer
• Basking area/heat source recommended
• UVB supplementation (UV index 1-4) - Reptisun 10.0 UVB T5 lamps, measure output with UV meter
• Humidity >60% in enclosure, >80% in burrows; aid with misting
• Adequate ventilation
• Enclosure minimum space: 3 m^2 floor space for each adult animal if housed alone and 5 m^2 if housed in a group
• Substrate should drain
• Substrate should be deep enough for digging burrows and nests
• Soil, leaf litter, addition of coarse sand or fine pumice for drainage; replace as needed
• Artificial burrows - partially buried hollow logs, plastic pipes, wooden boxes with hinged lids (inspection, capture)
• Cage furniture - shrubs and rocks, shade, visuals
• Shallow water dish - water source, soaking, pass urates, feces
• Smooth, non abrasive walls
• Enclosed with wire or mesh if outdoor to protect from predators
• House young separately from adults- predation
• Get territorial around 6 months; separate incompatible animals

Question 4

What is the diet of the tuatara?

Answer 4

Feeding and nutrition

• Variety of live invertebrates, occasionally in summer small bird eggs or newly hatched chicks.
• Insectivores - darkling beetles, weevils, spiders, earthworms, adult moths, tree weta, crustaceans if available.
• May also consume ripe kawakawa berries.
• Captive diet should mimic natural; vit/min supplementation.
• Zoo - live field crickets and locusts dusted with repashy calcium plus; woodlice, mealworm beetles, cockroaches when available.
• Secondary nutritional hyperparathyroidism and obesity occur similar to other reptiles.

Question 5

What anesthetics have been used in tuatara?

What drugs are recommended to be avoided?

What analgesics have been used in tuatara?

Answer 5

Chemical restraint

• Low metabolic rate can result in even longer recovery times compared to other reptiles
• Avoid ketamine - prolonged apnea and recoveries of 3 to 12 hours (wide reported dose range)
• Alfaxalone IM or IV at 5 mg/kg did not produce appreciable sedation but did prolong recovery from inhalation anesthesia
• Alfaxalone at 10 mg/kg IM or IV produced deep sedation to light anesthesia, recoveries up to 2 hours
• Auckland Zoo prefers iso/sevoflurane
• Breath hold on isoflurane - use tight fitting mask for partial ventilation, use medical air for induction (similar effects seen with sevo)
• Can be induced with sevo in dark chamber. Apnea during anesthesia is common.
• Intermittent positive pressure ventilation at 1-6 breaths per minute is frequently needed to maintain anesthesia
• Change from oxygen back to medical air asap before end of procedure to speed up recovery (10-30 min)
• Depth can be gauged by using the pedal withdrawal reflex.
• Meloxicam and butorphanol has been used.

Question 6

What are common causes of dermatitis in tuatara? Are there any predisposing factors?

What are some common tuatara parasites?

Are they prone to any metabolic conditions?

Answer 6

Medicine and Surgery

• Maximum body temp during and following surgery should not exceed 25C and suture removal should be delayed for 12-16 weeks.
• Mycoses:
  
  • Dermatitis.
    
    • Ranges from mild superficial brown discoloration of single or small clusters of scales often on ventral skin to raised, exudative plaques or necrotizing ulcerative dermatitis that can be fatal.
    • Associated with periods of cool, wet weather and resolves when animals are provided with drier, less exposed environments.
    • Topical antiseptic solutions may help.
    • Typically a combination of fungi and mixed bacteria.
      
      • Fungal isolates – Penicillium spp, Zygomycete-like organisms, Chrysosporium spp.
        
        • Tx has included itra or fluconazole, ceftaz, enro, meloxicam, terbinafine.
      • Avoiding prolonged exposure to extremes of cold and wet in winter and provision of adequate UVB exposure appear to be important preventative measures.
• Parasites:
  
  • Host-specific tick: Ambylomma sphenodonti.
  • Hemoparasite – Hepatozoon tuatarae.
  • Nematode – Hatterianema hollandei (Heterakidae).
  • Generally not associated with clinical signs. Nematodes have been treated with Panacur.
• Metabolic conditions:
  
  • Hypocalcemia during winter in a gravid female reported.
    
    • Responded to parenteral calcium borogluconate.
  • Juveniles prone to metabolic bone disease.
• Trauma:
  
  • Tail loss.
  • Bite wounds.

Wound management – Nanocrystalline silver-impregnated Acticoat under adhesive Hypafix dressing reinforced with tissue glue used with success, allows animals to remain on natural substrates