Resources gathered by animals

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Resources gathered by animals

• Food for energy and macromolecules
• Water
• Shelter from enemies (Enemy Free Space)
• Space
• Thermal energy
• Chemicals used for signaling

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Animals are Heterotrophs Plants are Autotrophs

• Heterotrophs are incapable of producing their own
  energy as plants do via photosynthesis
• Heterotrophs must consume food that contains
  energy, and both organic and inorganic chemical
  nutrients

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Some Animals obtain their food symbiotically

• Corals, and some sponges and jellyfish contain
  symbiotic algae that photosynthesize and transfer
  energy to their coral hosts in exchange for
  certain nutrients
• Thermal vent worms (Annelida Vestimentifera)
  obtain most of their nutrients from symbiotic
  bacteria in exchange for H2S and CO2 that they
  absorb from the water
• Some beetles (ambrosia) transport, farm, and
  consume fungi to obtain most of their nutrients
  and energy
• No animals can obtain all their energy without
  transfer from or consumption of other organisms

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Annelida Vestimentifera Thermal vent tube worms
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• For any animal, a nutritionally adequate diet is
  essential for homeostasis, a steady-state balance
  in body functions.
• A balanced diet provides fuel for cellular work
  and the materials needed to construct organic
  molecules.

• A nutritionally adequate diet satisfies three
  needs
• fuel (chemical energy) for all the cellular work
  of the body
• the organic raw materials animals use in
  biosynthesis (carbon skeletons to make many of
  their own molecules)
• essential nutrients, substances that the animals
  cannot make for itself from any raw material and
  therefore must obtain in food in prefabricated
  form.

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Homeostatic mechanisms manage an animals fuel

• The flow of food energy into and out of an animal
  can be viewed as a budget, with the production
  of ATP accounting for the largest fraction by far
  of the energy budget of most animals.
• ATP powers basal or resting metabolism, as well
  as activity, and, in endothermic animals,
  temperature regulation. However, most
  invertebrates are ectothermic their body
  temperatures conform to the ambient temperature
  of their environment

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• Nearly all ATP is derived from oxidation of
  organic fuel molecules - carbohydrates, proteins,
  and fats - in cellular respiration.
• The monomers of any of these substances can be
  used as fuel, though priority is usually given to
  carbohydrates and fats.
• Fats are especially rich in energy, containing
  twice the energy of an equal amount of
  carbohydrate or protein.

• When an animal takes in more calories than it
  needs to produce ATP, the excess can be used for
  biosynthesis.
• This biosynthesis can be used to grow in size or
  for reproduction, or can be stored in energy
  depots.

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An animals diet must supply essential nutrients
and carbon skeletons for biosynthesis

• In addition to fuel for ATP production, an
  animals diet must supply all the raw materials
  for biosynthesis.
• This requires organic precursors (carbon
  skeletons) from its food.
• Given a source of organic carbon (such as sugar)
  and a source of organic nitrogen (usually in
  amino acids from the digestion of proteins),
  animals can fabricate a great variety of organic
  molecules - carbohydrates, proteins, and lipids.

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• Besides fuel and carbon skeletons, an animals
  diet must also supply essential nutrients.
• These are materials that must be obtained in
  preassembled form because the animals cells
  cannot make them from any raw material.
• Some materials are essential for all animals, but
  others are needed only by certain species.
• For example, ascorbic acid (vitamin C) is an
  essential nutrient for humans and other primates,
  guinea pigs, and some birds and snakes, but not
  for most other animals.

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• Animals require 20 amino acids to make proteins.
• Most animals can synthesize half of these if
  their diet includes organic nitrogen.
• Essential amino acids must be obtained from food
  in prefabricated form.
• Eight amino acids are essential in the adult
  human with a ninth, histidine, essential for
  infants.
• The same amino acids are essential for most
  animals.

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• While animals can synthesize most of the fatty
  acids they need, they cannot synthesize essential
  fatty acids.
• These are certain unsaturated fatty acids,
  including linoleic acids required by humans.
• Most diets furnish ample quantities of essential
  fatty acids, and thus deficiencies are rare.

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• Minerals are simple inorganic nutrients, usually
  required in small amounts.
• Mineral requirements vary with animal species.
• Humans and other vertebrates require relatively
  large quantities of calcium and phosphorus for
  the construction and maintenance of bone among
  other uses.
• Iron is a component of the cytochromes that
  function in cellular respiration and of
  hemoglobin, the oxygen binding protein of red
  blood cells.

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The four main stages of food processing are
ingestion, digestion, absorption, and elimination

• Ingestion, the act of eating, is only the first
  stage of food processing.
• Food is packaged in bulk form and contains very
  complex arrays of molecules, including large
  polymers and various substances that may be
  difficult to process or may even be toxic.

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• Animals cannot use macromolecules like proteins,
  fats, and carbohydrates in the form of starch or
  other polysaccharides.
• First, polymers are too large to pass through
  membranes and enter the cells of the animal.
• Second, the macromolecules that make up an animal
  are not identical to those of its food.
• In building their macromolecules, however, all
  organisms use common monomers.
• For example, soybeans, fruit flies, and humans
  all assemble their proteins from the same 20
  amino acids.

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• Digestion, the second stage of food processing,
  is the process of breaking food down into
  molecules small enough for the body to absorb.
• Digestion cleaves macromolecules into their
  component monomers, which the animal then uses to
  make its own molecules or as fuel for ATP
  production.
• Polysaccharides and disaccharides are split into
  simple sugars.
• Fats are digested to glycerol and fatty acids.
• Proteins are broken down into amino acids.
• Nucleic acids are cleaved into nucleotides.

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• Chemical digestion is usually preceded by
  mechanical fragmentation of the food - by
  chewing, for instance.
• Breaking food into smaller pieces increases the
  surface area exposed to digestive juices
  containing hydrolytic enzymes.

• After the food is digested, the animals cells
  take up small molecules such as amino acids and
  simple sugars from the digestive compartment, a
  process called absorption.
• During elimination, undigested material passes
  out of the digestive compartment.

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Digestion occurs in specialized compartments

• To avoid digesting their own cells and tissues,
  most organisms conduct digestion in specialized
  compartments.
• The simplest digestive compartments are food
  vacuoles, organelles in which hydrolytic enzymes
  break down food without digesting the cells own
  cytoplasm, a process termed intracellular
  digestion.
• This is the sole digestive strategy in
  heterotrophic protists and in sponges, the only
  animal that digests food this way.

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• (1) Heterotrophic protists engulf their food by
  phagocytosis or pinocytosis and (2) digest their
  meals in food vacuoles.
• (3) Newly formed vacuoles are carried around the
  cell (4) until they fuse with lysosomes, which
  are organelles containing hydrolytic enzymes.
• (5) Later, the vacuole fuses with an anal pore
  and its contents are eliminated.

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• In most animals, at least some hydrolysis occurs
  by extracellular digestion, the breakdown of food
  outside cells.
• Extracellular digestion occurs within
  compartments that are continuous with the outside
  of the animals body.
• This enables organisms to devour much larger prey
  than can be ingested by phagocytosis and digested
  intracellularly.

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• Many animals with simple body plans, such as
  cnidarians and flatworms, have digestive sacs
  with single openings, called gastrovascular
  cavities.
• For example, a hydra captures its prey with
  nematocysts and stuffs the prey through the mouth
  into the gastrovascular cavity.
• The prey is then partially digested by enzymes
  secreted by gastrodermal cells.
• These cells absorb food particles and most of the
  actual hydrolysis of macromolecules occur
  intracellularly.
• Undigested materials are eliminated through the
  mouth.

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• In contrast to cnidarians and flatworms, most
  animals have complete digestive tracts or
  alimentary canals with a mouth, digestive tube,
  and an anus.
• Because food moves in one direction, the tube can
  be organized into special regions that carry out
  digestion and nutrient absorption in a stepwise
  fashion.

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• Food ingested through the mouth and pharynx
  passes through an esophagus that leads to a crop,
  gizzard, or stomach, depending on the species.
• Crops and stomachs usually serve as food storage
  organs, although some digestion occurs there too.
• Gizzards grind and fragment food.
• In the intestine, digestive enzymes hydrolyze the
  food molecules, and nutrients are absorbed across
  the lining of the tube into the blood.
• Undigested wastes are eliminated through the
  anus.
• This system enables organisms to ingest
  additional food before earlier meals are
  completely digested.

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Some animals use external digestion for the
initial stages of digestion

• Some seastars (Echinodermata) evert their
  stomachs out of their mouths to partially digest
  prey before retracting their stomachs back into
  their bodies
• Spiders inject digestive enzymes into the bodies
  of their prey before lapping up the resulting
  broth of partially digested prey tissues

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Animals feed on a variety of biological materials

• Animals fit into one of several dietary
  categories.
• Herbivores, such as butterflies and moths, and
  many snails, eat mainly autotrophs (plants,
  algae).
• Carnivores, such as wasps, jellyfish, spiders,
  and arrow worms (Chaetognatha), eat other
  animals.
• Omnivores, such as cockroaches, crabs, sponges,
  and Annelida, consume animal and plant or algal
  matter.
• Detritivores, such as earth worms eat dead plant
  material
• Scavengers, such some beetles (Dermestidae)
  consume the carcasses of dead animals
• Fungivores, such as some beetles and flies
  consume fungi
• Coprophages, such as some beetles and flies
  consume dung

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Chaetognatha arrow worm planktonic marine
predator
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Seastar predator with eversible stomach
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Animals use a diverse variety of adaptations for
feeding

• The mechanisms by which animals ingest food are
  highly variable.
• Many aquatic animals, such as clams, are
  suspension-feeders or filter-feeders that sift
  small food particles from the water.
• Many marine and aquatic animals, such as snails,
  limpets, and caddisflies are surface-feeders or
  grazers that consume bacteria, algae, and fungi
  on rocks, dead plant material, and other
  substrates

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Polychaeta fan worm a filter feeder
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• Deposit-feeders, like earthworms, eat their way
  through dirt or sediments and extract partially
  decayed organic material consumed along with the
  soil or sediments.
• Internal-feeders live in their food source,
  eating their way through the food.
• For example, maggots burrow into animal
  carcasses and leaf miners tunnel through the
  interior of leaves.

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• Fluid-feeders make their living sucking
  nutrient-rich fluids from a living host and are
  considered parasites.
• Mosquitoes and leaches suck blood from animals.
• Aphids tap the phloem sap of plants.
• Bees are fluid-feeders that inadvertently aid
  plants, by transferring pollen as they move from
  flower to flower to obtain nectar.

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Predators use different tactics to obtain prey

• Sit and wait predators such as crab spiders,
  ambush bugs, corals, ant-lions and anemones wait
  for their prey to stumble upon them rather that
  actively hunting for prey
• Active foraging predators such as wasps, ants,
  seastars, and some snails, seek out and subdue
  prey

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Parasites may be internal, external, or
parasitoids

• Many parasites such as tapeworms (Cestoda), some
  flies (Hippoboscidae, Sarcophagidae) live within
  their hosts tissues thus solving the need for
  food and shelter simultaneously
• Other parasites are merely attached to the
  surface of the host such as ticks (Acarina) and
  lice (Hexapoda Anoplura and Mallophaga)
• Among parasitic wasps and flies, the juvenile
  lives on or in the host body, but kills the host
  when the parasite matures. Parasites that kill
  their hosts are called parasitoids

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Water

• Most invertebrates obtain water from their
  aquatic environment, their food, or by metabolic
  production of water
• However, terrestrial invertebrates in desert
  environments may also collect water from dew, or
  have particular adaptations that reduce water loss

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Enemy Free Space

• Shells and Spines
• Feeding from burrows, webs, galls, mines, or
  other defensive structures
• Distastefulness
• Chemical exudates
• Feeding at night

• Crypsis and camouflage
• Disruptive coloration
• Warning coloration
• Mimicry
• Feeding commensally with a predator

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Mollusca - Shells
Bivalvia - Bivalves
Scaphopoda Tusk shells
Cephalopoda
Polyplacophora - Chitons
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Gastropoda - spines
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Feeding from defensive structures
Leaf mine and beak marks
Wasp gall, aphids, and ants
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Chemical exudates
Pieris rapae, cabbage butterfly
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Chemical Exudates
(A-C) Pupa of C. sanguinea responding to
stimulation with bristle of a fine paint brush.
The jaw-like "gin traps" on the back of the pupa
are ordinarily held agape (arrows in A).
Insertion of the bristle into a trap causes the
pupa to flip upward, with the result that the
bristle is "bitten". (D) Pupa of Mexican bean
beetle (E. varivestis), in dorsal view. Note the
glandular hairs, with glistening droplets of
secretion at the tip, that fringe the pupa. (E)
Enlarged view of glandular hairs of E. varivestis
pupa. (F) Ant (Crematogaster cerasi) that has
just contacted the glandular hairs of an E.
borealis pupa (left) with an antenna, cleaning
that antenna by brushing it with a foreleg.
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Feeding at night

• Many animals feed at night to avoid visually
  searching predators (moths)
• Crustaceans around reefs and in seagrass beds

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Warning coloration
Flabellina iodinea (Mollusca Nudibranchia)
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Crypsis
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Mimicry
Distasteful Palatable Model Mimic
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Mimicry
Chromodoris magnifica (Mollusca Gastropoda)
Pseudoceros sp. (Platyhelminthes Turbellaria)
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• PREDATOR-PREY INTERACTION PREYS VIEW
• C. AVOIDING CAPTURE
• 4. MIMICRY
• TEPHRITID FLY BY GREENE
• -TEPHRITID FLIES MIMIC PREDATOR BY WAVING
  PATTERNED WINGS

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• PREDATOR-PREY INTERACTION PREYS VIEW
• TEPHRITID FLY BY GREENE

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1. OTHER PREDATORS ATE ALL 5 FLY TYPES
2. JUMPING SPIDER RETREATED FROM A AND B

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Feeding commensally with a predator
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Shelter

• Lobsters feed from burrows
• Hermit crabs occupy empty shells of Gastropod
  molluscs
• Shrimp shelter in algal mats and grass beds and
  forage onto mud flats and sandy sea bottoms at
  night
• Many Annelid worms build protective tubes or
  burrows

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Space

• Many species of intertidal marine invertebrates
  compete for space to settle and attach to the
  substrate (barnacles, mussels, etc.)
• Settlement of larval invertebrates can be
  inhibited by the presence of chemical cues
  produced by competing or predatory species, and
  enhanced by cues produced by conspecifics

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Space
Anthopleura elegantissima - acrorhagi
Mytilus (mussel) and Pisaster (starfish)
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Acquiring Thermal Energy by Basking

• Some insects bask to increase their body
  temperature so that they can be active even when
  air temperatures are low
• Some insects sit in flowers which act like
  parabolic reflectors concentrating reflected
  sunlight on the insect and increasing its body
  temperature

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Chemicals for signaling and defense

• Called Pharmacophagy
• Observed in some adult Lepidoptera (moths and
  butterflies)
• Adult males which are non feeding collect
  pyrrolizidine alkaloids for sex attractants and
  larval defense
• Alkaloids passed to female with the spermatophore
  

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Pharmacophagy in Comosoma myodora
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Summary

• Invertebrate acquire resources in a wide variety
  of ways
• Food , followed by enemy-free space are the most
  important resources
• Even within groups of related animals there is
  considerable variety of feeding habits