The effect of the nasal anatomy on the behaviour patterns of the European elk (Alces alces)

Abstract

This final thesis suggests that the European elk’s (Alces alces) nose is anatomically unique when compared to reindeer and roe deer. The nasal bone has reduced in size, and the cartilages of the nose have enlarged giving the moose a distinctive appearance. This thesis aims to analyse explanations for the specific nasal anatomy in the elk and interpret which could connect the anatomy of the nose to their behaviour while introducing the evolutionary differences with other species. For this thesis, 37 European elk heads were collected from the hunters of Satakunta, Finland. Two reindeer and two roe deer specimens were also included. After, the analyzed data was used to make connections to the behavior of the elk. This thesis discusses temperature regulation adaptation of the nasal respiratory system and its extent to aid in the survival of the elk in the northern climate. The elk is classified as a selective browser and has numerous typical adaptations that may have influenced the anatomy of the nose. The European elk has separated nostrils, which has been suggested to allow an enhanced ability to locate the source of the olfactory signal. Enhanced stereoolfaction is hypothesized to be one of the reasons behind the nasal anatomical differences in the elk. This thesis suggests that aquatic foraging and diving could be an essential factor in the evolution of the nasal anatomy. The European elk is the only non-aquatic artiodactyl that forages in the aquatic environment. The nostrils unique narial structures and closure could be connected to the foraging method. The final thesis research revealed the elk has the shortest nasal bone compared to outgroups. The nostrils are situated furthest away from each other when compared to outgroups. The nasal turbinates are the longest of the studied species but proportionally take less space in the nasal cavity. The nasal cavity in the elk is enlarged volume-wise and lengthwise. The lateral nasal cartilages are farther away from each other than in outgroups. The nasal cavity is also more open due to the wider inner structures.

Antud kirjeldav lõputöö käsitleb põdra (Alces alces) nina anatoomiat võrdluses põhjapõdra (Rangifer tarandus) ja metskitsega (Capreolus capreolus) kes kuuluvad samuti hirvlaste sugukonda. Põdra ninaluu pikkus on vähenenud ja ninakõhred suurenenud ning ninal on omapärane välimus. Lõputöö eesmärgiks oli analüüsida põtrade nina anatoomia iseärasusi ning leida seoseid nina anatoomia ja põtrade käitumise vahel ning tuua välja erinevusi teiste hirvlastega võrreldes. Töö koostamiseks koguti Soome Satakunta jahimeestelt 37 põdra pead. Võrdlevanatoomiliselt uuriti 2 põhjapõdra ja 2 metskitse pead. Kogutud andmeid analüüsiti ja püüti leida seoseid põdra erinevate käitumuslike iseärasustega. Käesolevas töös arutletakse ka nina morfoloogia kohastumist kehatemperatuuri reguleerimisel kuna see soodustab põdra ellujäämist põhjamaises kliimas. Põder on selektiivne mäletseja, kelle nina ja tundlik ülamokk on anatoomiliselt kohastunud okste, lehtede, võrsete jms haaramiseks. Kuigi põdral on väike ninapeegel, on ninasõõrmete vahemik pikk, mis väidetavalt võimaldab paremini tuvastada lõhnade allikat ning suunda ehk kasutada nn stereohaistmist. Varasemates uuringutes on kirjeldatud spetsiaalseid anatoomilisi struktuure, nt padjandid ninaesiku seinas, mis võimaldavad ninasõõrmeid sulgeda. Taoline nina ehitus laseb loomal muuta õhu liikumist ninaõõnes ning kergendada sukeldumist hankimaks toiduks veetaimi. On ju põder ainus mitteveeline hirvlane, kes elab soode ja veekogude ligiduses ning otsib neist toitu.