Topic 6 - Modes of Feeding

Insectivores

feed on insects, arthropods, and worms

Insectivore dentition

• sharp teeth modified for piercing and crushing arthropod exoskeletons

• some very specialized & have sticky tongue instead of teeth (anteaters)

Insectivore digestive tract

short, less specialized digestive tract lacking cecum

Majority of what suborder are aerial insectivores?

microchiroptera

All bats between what latitudes are insectivores?

38°N & 40°S

Echolocation

ability to project sound waves & locate objects from reflection of sound waves

Skull modifications to insectivore bats

size of prey determines bat jaw morphology

Pallid bat insect specialization

large arthropods

Insectivore adaptations

• venom

• specialists feeding on colonial insects

• special sensory systems

4 insectivore species that produce venom

• haitian solenodon

• mediterranean shrew

• european water shrew

• northern short tailed shrew

Myrmecophagus

animals that feed on ants and termites

Myrmecophagy groups

• armadillos

• anteaters

• pangolins

• aardvark

• numbat

Myrmecophagy dentition

simple peg like teeth (or lost completely)

Myrmecophagy mouth and tongue

elongated & tubular

Myrmecophagy salivary glands

secretions high in mucus to make tongue sticky

Eimer organs

tactile sensory organs found on snout

Which family has eimer organs

family Talipidae (moles & desmans)

How is snout arranged in family talipidae?

arranged into bulbous papillae rich in tactile receptors to inc surface area of epidermis

Obligate carnivore vs. Facultative carnivore

Obligate: nutrients exclusively from meat

Facultative: nutrients mainly from meat (but can get from other sources)

Carnivorous animals

• most of order carnivora

• marsupial order dasyuridae

• some microchiroptera

Carnivore digestive tract

unspecialized like insectivores

Carnivore dentition

• canines long and pointed

• premolars & molars modified to process meat & crush bone

What jaw muscles are larger in carnivores?

temporalis: powers jaw

What jaw muscles are larger in herbivores?

• pyerygoideus

• masseter: facilitate chewing

Felid adaptations

• binocular vision

• sensitive vibrissea

• parakeratinized papillae on tongue (helps scrape meat off bone)

• obligate carnivore

Mustelids

• obligate carnivore

• most terrestrial

  • some semiaquatic (otter)

  • 1 marine (sea otter)

Canids

• facultative carnivores

• packs with complex social systems to inc hunting efficieny

All aerial carnivores are:

specialized microchiroptera

6 carnivorous bat families

• Hipposideridae: old world leaf nosed bats

• Megadermatidae: false vampire bats

• Noctilionidae: bullfrog/fisherman bats

• Nycteridae: hollow faced bats

• Phyllostomidae: leaf nosed bats

• Verspertiliondiae: vesper/evening bats

Only sanguinivorous mammals

vampire bats

Marine carnivores

• superfamily pinnipedia

• artiodactyl infraorder cetacea

Two cetacea parvorders

• odontoceti: toothed whales & dolphins

• mysticeti: baleen whales

Parvorder odontoceti modifications

• primarily piscivorous

• redeveloped homodontic dentition

• developed echolocation

Parvorder Mysticeti feeding

filter feeders using baleen (keratinized plates coming off of oral epithelium in upper jaw)

Browser & grazer herbivores

perissodactlys & artiodactlys

Gnawer herbivores

lagomorphs & rodents

Herbivore dentition

• canines lost/reduced

• molariform teeth shaped to crush/tear plant matter

• high crowned, hypsodont

Rodent & lagomorph incisors

modified to continue growing to allow for gnawing

How do herbivores chew

side to side

What happened to the dentary in herbivores?

deeper angle to anchor large masseter

Multichambered stomach

Digastric stomach

Ruminant vs. Pseudoruminant stomach

ruminant: 4 chambered digastric

pseudoruminant: 3 chambered digastric

Simple stomach

monogastric stomach

Ruminant digastric animals; Pseudoruminant digastric animals

Ruminant: artiodactyls, macropods, tylopods (camels)

Pseudoruminant: hippopotamids

Monogastric animals

perissodactlys, lagomorphs, rodents

Herbivore intestinal tract

longer intestines; can include well-developed cecum

What is the problem with a plant based diet?

mammals don’t produce cellulase & need to use fermentation to break down cellulose

What stomachs use foregut fermentation?

digastric stomachs; ruminants

Ruminant stomach

animal swallows food → stores in first chamber → regurgitates & chews → swallows back into stomach

Fermentation division (ruminant stomach)

1st division to receive food

2 portions

• Rumen

• Reticulum

Rumen

site of microbial fermentation

Reticulum

• honey-combed appearance

• fluid contents separate particles

  • send cud back to esophagus for regurgitation

True stomach

2nd divison

2 portions

• Omasum

• Abomasum

Omasum

• receives food from reticulum

• absorbs water, and other molecules produced from fermentation that haven’t been absorbed into the bloodstream yet by fermentation division

Abomasum

secretes enzymes for chemical digestion

Pseudoruminant stomach foregut fermentation

• lack rumen

• reticulum plays roles as foregut fermenter

  • doesn’t account for enough fermentation

  • supplemented by cecum

Hindgut fermentation

cellulose digested with aid of symbiotic bacteria in large intestine & cecum

Large animals that are hindgut fermenters

use large intestine

Small animals that are hindgut fermenters

use cecum

Which rodent family lacks a cecum? Why?

dormice (family Giridae); low cellulose diet

Coprophagy

• still lots of nutrients in food first time it is defecated due to fermentation process occurring after small intestine

• consuming feces first time they have passed through digestive tract to harvest nutrients made available through fermentation

Graminivores

• feed on grasses

• hypsodont teeth

• wider mouths on anterior portion

Folivores

• feed on leaves

• prefer immature leaves: easier to chew, lower in cellulose & poisons

• flexible upper lip & tongue

Frugivores

• feed on fruits

• dec # of molars & retained sharp canines

• important role in seed dispersal

Granivores

• feed on seeds & nuts

• adapted cheek pouches

Nectarivores

• feed on nectar

• elongated tongue & muzzle

• reduction in size/# of teeth

Omnivores

• unspecialized, opportunistic generalists

• complete dentition & bunodont teeth

Foraging theory

behavior ecology that studies foraging behavior of animals in response to enviro where animal lives

Optimal foraging theory

organisms forage in a way to maximize their net energy intake per unit of time

Optimal foraging theory formula

E/h

E: amount of energy (calories) from prey item

h: handling time (capture, killing, eating, digesting)

When does h start?

once prey has been spotted

Playnivores

feed on pollen

Mucivores

feed on plant fluids (ex. sap)

Xylophages

feed on wood