Overarching Theme Adaptation ANIMALS What characteristics do all
animals share?What are the important trends in animal evolution?
Big Idea Annelids and Arthropods were first to develop adaptations
such as segmentation.PHYLUM ANNELIDA Segmented WormsGeneral
Characteristics Bilateral symmetry Three germ layers Coelomates
Long, segmented body, each segment separated by internal walls
called septa segments allow for specialization of tissue and
efficiency of movement longitudinal and circular muscles which help
in locomotion Complete digestive tract with mouth and anus at
opposite ends: tube-within-a-tube Found in variety of habitats such
as moist soil, fresh and salt water have the most developed sense
organs seen thus far, especially in marine species sensory cells
are receptive to chemical, mechanical and light stimuli most
undergo sexual reproduction but some species can reproduce
asexually by budding and regeneration TaxonomyClasses
A) Oligochaeta (= few bristles) e.g. earthworm & tubifex
worms (fish food)- live in soil or fresh water, some in oceans-
setae (bristles) on ventral side of bodyi) Feeding and Digestion-
pharynx can extend through mouth- detritus feeders jaws covered in
sticky mucus or act like pump to suck up food- earthworms form
castings through digestion, this is major component of soil- food
goes in mouth -> to crop (temporary storage) -> gizzard
(grinds food into small pieces) -> to intestine (enzymes
breakdown food) -> digested food absorbed into blood -> waste
out anus (castings)
ii) Reproduction- permanent sex organs, hermaphroditic but must
cross fertilize- two worms crawl into mating position and release
mucus from clitellum, a dorsal, saddle-like swelling to aid in
transfer of sperm- transfer sperm to sperm receptacle of each
other- worms separate- mature ova and sperm shed in cocoon made by
clitellum, fertilization external- zygote develops into microscopic
ciliated larvae, then into baby earthworms
iii) Respiration- diffusion through moist skin- secrete a
protective coating (=cuticle) to hold in moisture and produce a
layer of mucusiv) Circulation- have a closed circulatory system,
this is another evolutionary step and first appeared in annelids-
two blood vessels run length of body- to head via dorsal vessel and
to tail via ventral vessel- ring vessels in each segment supply
blood to internal organs- five pairs of pulsating aortic arches
(mini hearts) direct blood flow to specific regions of body
v) Excretion - paired nephridia in each segment, these are
simple, tube-shape excretory organs that direct metabolic wastes to
outside of body through minute pores in the cuticle- solid wastes
go out anusvi) Nervous System- paired ventral nerve cord runs
length of body- anterior dorsal bi-lobed ganglion (primitive
brain)- nerves branch into each segment from nerve cordvii)
Movement- two types of muscles longitudinal muscles: front to rear,
allow animal to contract and expand in length circular muscles:
encircle body, when they contract animal gets skinnier, this allows
then to force their way through sediment/soil- setae push into soil
and prevent worm from slipping backwardsviii) Ecological Role-
break down organic matter- mix and aerate soil- important in
composts- are eaten by many birds and other animals
Learning Activity Earthworm Sheet and Dissection
B. Polychaeta (=many bristles) e.g. sand worms, tube worms, clam
worms- marine worms - variety of habitats; live in cracks &
crevices in coral reefs, sand, mud, piles of rock, open water,
burrow, in tubes- paired parapodia (paddlelike appendages) tipped
with setae (bristles) on segments- parapodia used for walking,
digging, as fins may be precursors of legs seen in later animals-
e.g. sea mouse long bristles extend over back of worm (furlike)-
well developed eyes, antennae, and sensory palps- mostly predators
either by filter feeding (e.g. tubeworms have featherlike
structures to sift detritus and plankton from water) or active
hunters (sandworms hide in burrows and use powerful jaws to clamp
onto prey)- external fertilization forms trocophore (ciliated
larvae) juvenile worms adults - exchange gases using gills, e.g.
Feather Duster, have large, coloured, feathery gills that protrude
from burrow or tube- convert organic debris in oceans into CO2 used
by marine plankton for photosynthesis C. Hirudinae (no bristles)-
external parasites e.g. leeches, suck blood and tissue fluid- found
in moist tropical countries - < 6 cm long, some tropical ones
are 30 cm!- freshwater, some marine & terrestrial- are
carnivorous not parasites eat invertebrates (snails, worms, larva)-
oral chaetae (teeth) are specialized to pierce skin of host-
produce and secrete hirudin, a chemical substance that has both
anaesthetic and anticoagulant properties- powerful suckers at both
ends that help them cling to their host- muscular pharynx sucks
blood- can suck up to 10 times its weight in blood in 1 feeding-
takes up to 200 days to digest its blood feast (with symbiotic
bacterias help)- can live 1 year before next feeding- as with other
parasites, do not have significant nervous, digestive, excretory or
circulatory systems- reproduce in manner similar to earthworms- can
be used by humans to maintain blood flow after microsurgeries,
reduce swelling and speed up healing of tissues
PHYLUM ARTHROPODA Arthro=jointed, Poda=feet
General Characteristics 3 cell layers Bilateral Symmetry. Coelom
High degree of cephalization Jointed appendages 3 body regions
(head, thorax, abdomen) segmented body shows evolutionary
relationship with annelids, most clearly seen in Chilopoda,
Diplopoda and larval (like caterpillars) stage of some Insecta
Exoskeleton of chitin + protein: secreted by the epidermis
(pro-good protection, con-only moves at joints, cannot get bigger,
so must molt) Most dominant and widespread life form on Earth 70-
85% of all animals are arthropodsi) Respiration - use one of three
structures - gills, tracheal tubes, or book lungs (see diagram)-
terrestrial arthropods depend on respiratory system with tracheal
tubes rather than circulatory system to carry O2 to cells- spiders
and other arachnids use book lungs- aquatic arthropods use gills in
similar manner to mollusksii) Nervous System Sensory organs are
well-developed: compound eyes, tympanum (ear), antenna (touch,
smell, chemical reception). dorsal brain, connected by a ring and a
double nerve cordiii) Feeding and Digestion Mouthparts usually
include pair of mandibles for biting and chewing Digestive system:
complete, mouth, intestine and anus. Glands produce digestive
enzymesiv) Movement Locomotion: many different adaptations for
movement such as walking legs, wings, swimming appendages Quick,
active animals with well-developed muscle systemv) Reproduction-
dioecious= separate sexes (except for a few such as barnacles)-
fertilization usually internal- sexual reproduction vi) Excretion -
solid waste out anus, - metabolic waste out malpigian tubules in
terrestrial arthropods, out green glands (modified nephridia) in
aquatic arthropodsvii) Circulation- open circulatory system -
dorsal vessel acts as a heart, which delivers body fluids to
tissues throughout body chamberviii) Ecological and Economic Role-
Arthropods as Food:- Crab, lobster, shrimp, crayfish many coastal
economies rely on these- Foods for birds and insects- Zooplankton
and small crustaceans (krill) are food for fish and aquatic
mammals- Honey-bee: produces honey and royal jellyBeneficial
Arthropods:- Spiders: control aphids- Bees: pollination, wax,
honey- Silk: larvae of silkworm mothHarmful Arthropods:- Locusts:
destroys crops- Mosquito: carries diseases- Barnacle: foul bottom
of ships- Termites: destroys wood- Spiders and scorpions: poisonous
bites
Confirm your Knowledge Insect Rsum Assignment, due
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ix) TaxonomyPhylum Arthropoda is so huge that it is divided into
four subphyla, which are in turn divided into classes.Subphyla:1.
Trilobita -extinct now, fossils show development of exoskeletons,
jointed appendages and three body segments2. Chelicerata All
chelicerates have a body divided into a cephalothorax (fused head +
thorax) + abdomen Unique to chelicerates are two pairs of
appendages attached near mouth: chelicerae (spiders use these to
bite and paralyze prey, they then inject enzymes that liquefy the
prey and they suck the juice out) pedipalps (usually for handling
prey; in scorpions, modified into huge claws) All spiders produce
silk. Some spin webs using spinnerets, are abdominal appendages
Ticks and mites are usually parasites Silk used for webs,
protecting eggs and capturing preyi) Class Arachnida Spiders,
scorpions, ticks, mites All have 4 pairs of walking legs Most are
carnivorous ii) Class Merostomata Horseshoe crabs: living fossils,
basically unchanged for 200 million years! Not really crabs (lack
antennae and segmented abdomen of crustaceans) Catch food with
their chelicerae Eyes on sides of their carapace (shell)
3. Crustacea (subphylum and class) Includes all crustaceans:
crabs, prawns, lobster, crayfish, copepods, water fleas, barnacles
Primarily aquatic Vary widely in size microscopic to 6m Usually
have a very hard exoskeleton reinforced with calcium salts Usually
have 2 pairs of antennae and a pair of mandibles 5 pairs of walking
legs, with first pair specialized into pincers for grasping Have
head, thorax and abdomen Head and thorax can be fused into a
cephalothorax Appendages vary greatly; crayfish have claws, walking
legs, swimmerets and uropod Have bristles over body, sense
organs
4. Uniramia - millipedes, centipedes, and all insectsi) Class
Chilopoda 12 | Page
1 pair of legs per segment Centipedes are carnivores poison
fangs very fast
ii) Class Diplopoda 2 pair of legs per segment Millipedes are
scavengers Fairly slow Moist habitats
iii) Class Insecta Huge group, 76% all animal species All have a
head, thorax and abdomen 3 pair of legs attached to the thorax
Include herbivores, predators, parasites, scavengers social
behavior of many species, division of labour, these allow for
success of this class
Learning Activity Stations Lab
Insect Adaptations Insects have structural and functional
adaptations that have enabled them to become the most abundant and
diverse group of arthropods. About 80% of all arthropods are
insects
Metamorphosis: abrupt and pronounced changes in appearance (egg
to an adult)4 types of metamorphosis:1. No Metamorphosis: egg,
young adulte.g. Silverfish
2. Incomplete Metamorphosis: egg, naiad, adulte.g. dragonfly or
mosquito1. Egg: laid in water2. Naiad: is aquatic (grows by
molting)3. Adult: aerial (flies)
3. Gradual Metamorphosis:e.g. grasshopper1. Egg2. Nymph3.
Adult
4. Complete Metamorphosis:1. Egg2. Larvae (segmented)
caterpillars, grubs.3. Pupae (resting period) cocoon4. Adult: no
further molting. 90% of insects go through this stage
Molting (occurs in other arthropods as well such as Crustacea
and Chelicerata) Epidermis digests inner part of exoskeleton and
absorbs much of chitin to recycle Secretes new exoskeleton inside
of the old one, then pulls out of old one Often eats the leftovers!
Why waste good nutrients? Expands, puffs out to new size Takes a
few days to harden, vulnerable Molts several times (depends on
species) b/w hatching and adulthood
Legs- adapted to a variety of functions depending on habitat and
food source
Wings- insects are only invertebrates that can fly- has allowed
them to disperse long distances and colonize wide variety of
habitats- wings are outgrowths of body wall made of thin double
membrane of chitin (how are these different than vertebrate animal
wings?)- for flight, need adaptations for complex coordinated body
movements to ensure upward lift, balance and steeringMouthparts-
all insects have three pairs of appendages used as mouthparts but
these are adapted to type of food insect eats
- grasshoppers have piercing mouthparts to cut plant tissue
(mandibles) and other mouthparts to bring food into mouth (palps)-
butterflies and moths have long tube that is coiled and uncoiled to
draw nectar from flowers, like sipping through a straw- mosquitoes
have thin, needlelike tubes to pierce skin to suck liquids into
mouth- flies have a fleshy end to their mouthpart that acts like a
sponge to mop up foodInsect Societies- insects such as honeybees,
termites and ants organize into social groups and cooperate in
activities necessary for their survival- within a society,
individuals are specialized to perform specific tasks- also have
created adaptations for communication techniques; in the honeybee,
the waggle dance is used to tell others where food is located in
their habitat- other communication can be done visually (e.g.
bioluminescence in fireflies), by sound (grasshoppers rubbing legs
against wings), touch (ants touching antennae to pass on messages),
or chemically (trail pheromones used by caterpillars to create map
to food source that others can follow)
Connections to Biological Theme Describe the evolutionary
advantage of body segmentation, first seen in annelids.Segmentation
of the body plan is important for allowing different regions of the
body to develop differentially for different uses. But why should
segmentation be so advantageous? Over millions of years, and
exposure to changing environmental constraints, it is easier for an
animal to specialize a segment into a specific tool in response to
a need, than to create a whole new organ from scratch.
In 2010, researchers found that the genes controlling segment
formation during embryo development are almost the same in
drosophila (an arthropod) and in annelid marine worms, on which
they concentrated their studies. These similarities led them to
conclude that the genes had been inherited from a common ancestor,
which was itself segmented. It also appears that vertebrates
inherited this characteristic from an ancestor they share with the
arthropods and the
annelids.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Evaluate three adaptations of insects in terms of the role they
played in enabling insects to become so diverse and
abundant.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________