Endotherms 4 Flashcards
What are the classifications for feeders?
Herbivores, Carnivores and Omnivores
There are also suspension feeders, substrate feeders, fluid feeders and bulk feeders
What are the general features of bird nutrition?
Small homeotherms require high levels of nourishment which means that birds can starve to death within hours, particularly as food storage is typically avoided due to the effecto f weight on flying
They have a faster and more efficient digestive system than other vertebrates and can quickly increase body fat reserves
What is the importance of the mouth to birds nutrition?
The mouth is relatively unimportant, there are no teeth
The bill however is important with its shape reflecting the diet of the bird
The tongue is also important but for the sensing of texture rather than taste
They may or may not have salivary glands
What is the role of the esophagus in the digestive system of birds?
It is different to that of most other vertebrates
it holds excess food intake before processing
contains an enlarged portion or specialized lobes known as the crop
Some species such as Hoatzin employs foregut fermentation which occurs in both the crop and lower esophagus
What is the role of the crop in the bird digestive system?
This specialised portion of the lower oesophagus can be used to store food for nestlings and it may produce crop milk in species such as rock doves (this is similar to mammalian milk)
Produces a-amylase which is similar to mammalian saliva
What is the role of the stomach in the bird digestive system?
The form of this organ is related to the diet of the bird with carnivorous and piscivorous species as insects and seed eaters need muscles for physical breakdown
There is a proventriculus which is the anterior glandular stomach which secretes acid and digestive enzymes
There is also a gizzard which functions in storage during breakdown and mechanical processing with thick muscular walls for squeezing and stones for grinding
What is the role of the intestines in the bird digestive system?
The small intestine is the principal site of chemical digestion with enzymes being secreted from pancreas and intestine and absorption occurring across its wall
this is followed by the ceca which pair at the junction of a small and large intestine which assists with fermentation of plant material
The cloaca is then used to store waste to facilitate water reabsorption
Where in mammals are the adaptations to the type of food eaten most clearly seen?
In dentition, skull/jaw morphology and muscles, gut anatomy and physiology
What are diphodonts?
These are organisms which only have 2 sets of teeth in a lifetime and is seen in mammals with other vertebrates replacing teeth continuously leading to the problem of teeth durability
What are the different types and functions of teeth?
There are incisors which function to grab food and are enlarged in animals that gnaw and can grow continuously over lifetime
Canines which stab prey but are also used in secondary signalling like in walruses for sexual selection and retained in others for fighting like mouse deer
Premolars which function to pierce and slice, have a single cusp and are used as molars in some species
Molars which break food into fine particles and contain 3 or more cusps
What are the specialisations in dentition in herbivores?
There is no need to subdue prey so the canines are reduced or lost
There are small incisors
May use the entire post canine tooth row for mastication
Premolars resemble molars
The teeth are lophed meaning that they run together into ridges and the enamel is worn off to form blades as well as having specialisations which assist in durability
What are the adaptations seen in dentition in omnivores and frugivores?
The originally pointed cusps on molars have become flattened
There are bunodont teeth meaning a 4th cusp has been added to the upper molars to increase contact area with the lower molar
What are the dentition adaptations seen in carnivores?
There are enlarged canines and carnassials which are sheering canines made of the last premolar in the upper jaw and first in the lower jaw
What are the stomach and intestinal adaptations seen in mammals?
Carnivores have expandable stomachs probably due to the long time between meals so must be able to take on as much as possible
Herbivores and omnivores have longer alimentary canals than carnivores relative to body size due to the fact that plant material takes longer to digest and absorb, this longer tract helps in the function due to its greater surface area
Why is there are split between hindgut and foregut fermenters?
While animals are able to rupture cell membranes no multicellular organism can break down cellulose due to a lack of cellulose
This results in the formation of a symbiotic relationship with microbes which can convert cellulose and lignin into nutrients
This process occurs in specialised chambers and is known as fermentation depending on where this chamber is located will determine if it is a hindgut or foregut fermenter
