Adaptation. Skeletal System. Respiratory System 25/06/2013

Transcription

1 Adaptation Written by Elizabeth Hawkins for the Southern Cross University Biology & Conservation of Marine Mammals Unit 2013 Anatomy Muscular system Anatomical system that allows animal to move Specifically adapted to the marine environment E.g. Blowhole: muscular flap that provides airtight seal Myoglobin oxygen-binding protein stores oxygen Skeletal System Light & spongy bones Have forelimbs Remnant hind limbs Collapsible rib cages Respiratory System Cetaceans exchange 85-90% of air in one breathe (humans 15%) More red blood cells than human Oxygen rich blood (high levels of oxygen in muscles) Muscles can function anaerobically Can tolerate high levels of CO2 & can continue to dive with no oxygen 1

2 Circulatory System Heat Exchange System (Thermoregulation) keeping warm in a cold sea - Arteries in the extremities; dorsal fin, pec fins & tail flukes - Countercurrent heat exchange maintains body heat - Heart rate slows during a dive to lower metabolism Diving Adaptation Digestive System Three chambered digestive system Fore stomach begins digestion of food Major digestion takes place in second (main) stomach Pyloric stomach final digestion before transferred into the intestinal system Renal System The kidneys of dolphins are specially designed to filter the high levels of salt Multiple renules in kidneys that act as a separate kidneys and filer the salt Cetaceans stay hydrated from the food they eat Reproductive System Internal reproductive organs Large testes Unique feeding behaviours The Brain Large brain mammals Brain body size ratio (encephalization quotient (EQ)) is one of largest in animal kingdom (next to humans) Large cerebellum Cerebral hemisphere have larger surface area & nerve cells than humans Brain atlas: rains/brains/dolphin/mo vies/tcor80.mov 2

3 Fewer fibres (corpus callosum) between hemispheres - likely linked to semi-hemisphereical sleep patterns Vestibulocochlear nerve and acoustic regions of brain larger than terrestrial animals Large portion of brain dedicated to acoustic reception & information processing video How & Why Cetaceans Die? Necropsy Assessment & insight into cause of death Record relevant observations from internal and external assessments Management Implications Safety Personal & public safety are primary considerations Zoonotic organisms Protective equipment (gloves, glasses, bandage wounds, face masks etc.) Chemical handling Disposal of carcass Presence of bystanders 3

4 Procedure History of animal field assessment Transport/storage Necropsy Document everything Animal History (field information) Field assessment Date & time of stranding Location Environmental conditions Species identification Behaviour before & during Single or mass stranding Time of death Level of decomposition (fresh, moderate, advanced, mummified) Euthanized or natural death External scarring/lesions Parasites Debris/ entanglement Record of trauma Mode of carcass storage prior to necropsy Morphometrics Allows for understanding of species age estimation, growth rate, reproductive status & disease processes Body measurements (in cm) - e.g. Length, girth, dorsal length etc. Age estimation Teeth worn, missing Teeth count upper & lower jaw & obtain sample Sex determination Female 4

5 Eyes discolouration, injuries, discharge Blow hole description, discharge etc. Lactation Measure lesions & scars Sample parasites Photographically record all features Male Dolphin pox Lamprey bites Necropsy Procedure Dissections & Incisions Initial incisions pectoral fin/shoulder blade anus Blubber thickness (measure mm), colour & texture Muscle colour & volume Remove rib cage & systematically assess Assessment of internal organs trauma, tumours, haemorrhaging/trauma, parasites & cysts Lungs colour, sponginess, presence of fluid ect. Heart Diaphragm Stomachs - look for contents & degree of digestion & volume of fluids Liver colour & texture Kidney colour & texture Spleen Intestines colour & contents Reproductive Organs look for abnormalities & pregnancy Fore Stomach Pyloric Stomach Main Stomach 5

6 Dorsal Stomach Intestines Pyloric Stomach Adrenal Kidney Liver Intestines Ventral Sampling Sampling methods should ensure that differential diagnosis can be considered Labels must be clear & systematic Samples of: Blood (immediately after death only) Blubber Muscles Teeth Organs Lungs, liver, kidney, heart Parasites, tumours, cysts Other samples of interest e.g. Fluid excretions, milk etc. Brain fresh carcass only Specimen Collection & Storing Sample Storing Check Teeth Ageing Freeze Skin Genetics 70% ethanol or 10% DSMO or salt or freeze Toxicology: Blubber, liver, muscle, kidney Swabs Contaminants For fluid or unusual discharge Freeze samples in foil & place in zip-lock bag Freeze How to assess cause of death Human interaction Field Observations Necropsy assessment Histopathology: Lung, liver, kidneys, heart Blood 10mm slices; 10% buffered formalin Chill (obtained at time of death only) Parasites Identification 10% formalin or 70% ethanol Stomach Contents Identification 70% ethanol or freeze 6

7 Causes of death Natural Illness, disease, viruses Fungal & bacterial infestations Predatory attach Malnutrition/starvation Congenital defects Trauma Dehydration & sunburn Prenatal/neonatal mortalities Old age Human Related/Induced Toxins & Pollutants Fishing Interactions Ship/boat Strike Sonar Exposure Quality of food (habituation to human food sources) Gun shot wounds Stab wounds/ knife cuts Gas embolism? Entanglement 7

8 Management Implications Management of human-related causes Monitoring of population health Conservation initiatives Useful References Dolphin Anatomy & Pathology: **Pugliares, K. R., Bogomolni, A., Herzig, S. M. et al. (2007) Marine Mammal Necropsy: An introductory guide for stranding responders and field biologists, Technical Report, Woods Hole Oceanographic Institute, USA All in the Mind Radio National diving into dolphin heads: science, rights & ethics (available online)_ 8