Chapter 33: Invertebrates (Part III)
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Chapter 33: Invertebrates (Part III)
Phylum Nemertea aka..?
Characteristics of Nemertea (ribbon worms):
Cylindrical to flattened and very long
Most are marine, few freshwater or live in humid terrestrial habitats
Most range from 10 to 20 cm long
reported to reach 60 meters!
_______ is reported to reach lengths of 60 meters!
A type of ribbon worm
The ____ body plan resembles that of a flatworm.
The nemertea (ribbion worm) has some ____ with ____ lateral nerve cords.
fluid-filled sac that serves as hydraulic power sources for proboscis
True or false: Nemertean (ribbon worms) are gonochoric
True. aka male and female worms
How do ribbon worms reproduce?
Typically sexual reproduction.
Some asexually via fragmentation but may fragments die and do not form a new animal.
Phylum Annelida aka:
Characteristics of Phylum Annelida:
Brain or cerebral ganglion and sensory organs at anterior
Many species have eyes(earthworms don't)
Head and tail develop first then segments form between them
segments divided by septa
each segment has pair of excretory organs, a ganglion, and locomotory structure (marine annelid segments also have reproductive organs)
closed circulatory system
ventral nerve cord connects ganglia in each segment with another and the brain
What is the advantage of segmentation, such as in Annelids?
Development and function of individual segments or groups of segments can differ
Which species of annelids DO NOT have eyes?
How do the segments in Annelids develop?
Head and tail develop first
Segments form between them
True or False: The segments found in Annelids are not divided by septa
False, they are!
Do annelids have an open or closed circulatory system?
How do annelids move?
By contracting circular and longitudinal muscles against the hydrostatic skeleton.
Define Chaetae (setae)
Bristles that help anchor annelids in substrates so they don't slip when they move
What are the two classes of Annelida?
: Earthworms and Leeches
Annelid Class Polychaeta:
Parapodia-fleshy, paddle-like lateral projections used for swimming, burrowing or crawing
Parapodia also have important role in gas exchange; in some species they are modified into gill-like structures
Predatory polychaetes have powerful jaws
Sedentary tube worms have feathery tentacles for filter feeding as well as gas exchange
Most polychaetes are gonochoric and fertilization is external
Fertilization>spiral clevage>ciliated mobile trochophore larve>growth to adult
Polychaetes are (freshwater/marine) worms
Fleshy, paddle-like lateral projections used for swimming, burrowing, or crawling
Other than for movement, what is the other important role of parapodia?
gas exchange, some species have modified them into gill-like structures
Fertilization is _____ in polychaetes.
Characteristics of Palolo worms:
gamete-filled terminal parts considered a delicacy by some South Pacific natives
Class Clitellata aka:
Earthworms and Leeches
Earthworms were formerly in class Oligochaeta and leeches were formerly in Class Hirudinea. Why were they merged together?
Because they both have a clitellim!
A thickened band on the body that secretes mucus to hold worms together during copulation and to form a cocoon for fertilized eggs to develop.
Do polychaetes have a clitellum?
No! Poly wants a clitellum.
Head is not well developed
few chaetae & project directly from body wall
Eat their way through soil
No eyes, but do have light-, chemo-, and touch-sensitive cells
Eggs develop into young worms similar to adults
Most are freshwater, few are marine, some live in tropical terrestrial areas
Clitellum only develops during mating season!
Suckers at both ends of body
Coelom reduced and not segmented
no chaete (except one species)
eat detritus or devour small animals
some suck blood--secrete anesthetics and hirudin
What do earthworms and leeches have in common?
Both have a clitellim
What are some differences between Earthworms and leeches?
Earthworms do not have eyes
Leeches only develop a clitellum during mating season
Leeches are mainly freshwater
Phylum Arthropoda aka:
The most successful of all animals
Two-thirds of all animals are arthropods
Great economic importance of Arthropods:
food for humans and other animals
Damage to crops; insects are voracious herbivores
Carriers or spreaders of disease to plants and animals including humans
Four extant plus one that is extinct (CCHMT):
: spiders, mites, ticks, horshoe crabs
: crabs, shrimp, lobsters, barnacles, pill bugs
: centipedes, millipedes
: trilobites (extinct)
What is the most successful of all animals?
Arthropod key features-Mouthparts:
Chelicera (pincers) in chelicerates
Mandibles (biting jaws) in hexapods, crustaceans, and myriapods
Segmentation in Arthropods:
Body segments look alike in some arthropods
: the fusion of segments into specialized functional groups
: head, thorax, abdomen
In some arthropods, head and thorax are fused to form a
fusion of segments into specialized functional groups.
: head, thorax, abdomen
Exoskeleton in Arthropods:
Made of chitin and protein
provides antagonism for muscles, support for body, protection against physical forces
Can protect against water loss
The exoskeleton in arthropods is made of ____ and ___.
Chitin and protein
Limitation to arthropod exoskeletons include:
Size (weight gets too great with increased size)
Rigidity (must undergo ecdysis or molting)
Jointed appendages in Arthropods:
May be modified into antennae, various kinds of mouthparts, legs
Can bend to extend or retract
Joints serve as fulcrum for appendage movement so leverage is possible
Circulatory system of Arthropods
Open circulatory system
Heart pumps blood anteriorly
Blood flows towards posterior through spaces between tissues, when heart relaxes blood returns to posterior region of heart through one-way valves.
Nervous system of arthropods:
Double chain of segmented ganglia along ventral surface
three fused ganglia form brain
functions such as eating, moving, copulation, can be carried out even when brain is removed.
compound eyes composed of ommatidia (individual visual units)
ocelli= simple eyes present in some arthropods
Individual visual units that form compond eyes in arthropods.
Simple eyes present in some arthropods
Respiratory system in Arthropds:
: in marine crustaceans
: horseshoe crabs
outer epithellium or gut for gas exchange
: in some tiny arthropods
: in terrestrial arthropods; tracheae branch into tracheoles
: openings in exoskeleton where air enters, can be closed to prevent water loss
: in many spiders
Book gills vs Book lungs:
: horseshoe crabs
openings in exoskeleton where air enters; they can be closed to prevent water loss
Excretory system in arthropods
In aquatic arthropods, waste diffises from blood in gills
Malpighian tubules occur in terrestrial insects, myriapods, and chelicerates
Occur in terrestrial insects, myriapods, chelicerates
slender projections from digestive tract
attached at junction of midgut and hindgut
tubules contain fluid, are nitro-genous wastes from blood that bathes tubules
precipitated as uric acid or guanine that are then emptied into hindgut for elimination
water and salts are reabsorbed by hindgut and returned to arthropod's body
Key adaptation to life on land
______ in arthropods are key adaptations to life on land.
Class chelicerata contains:
Spiders, mites, ticks, scorpions, daddy long-legs, horseshoe crabs
Pair of chelicera (fangs or pincers)
Pair of pedipals
foud pairs of walking legs
mostly carnivorous, but mites are mostly herbivorous
Chelicerates have ____ tagmata. Which section bears all appendages and opisthosoma?
The anterior prosoma bears all appendages and opisthosoma
copulatory organs in male spiders
large pincers in scorpions
sensorial in most other chelicerates
Name the two orders found under Class Chelicerata:
: Mites and Ticks
From phylum Chelicerate
Important as predators of insects
produce silk that is forced out of spinnerets
all spiders have poison glads with channels through their chelicerae
poison/venom paralyzes prey
Wolf spiders and tarantulas prefer to ___ than spin webs.
Bites from ____ and ____ can be fatal to humans and large mammals.
black widows and brown recluse
Mites and Ticks
found in every habitat
predators and parasites of various organisms
most mites less than 1 mm long
in mites, cephalothorax and abdomen fused into ovoid body
Respiration using tracheae or directly through body surface
ticks are blood-sucking parasites of humans and other animals
In ____ the cephalothorax and abdomen are fused together forming a ____ body.
Some ticks carry disease-causing agents such as:
Rocky Mountain spotted fever
Red-water fever (affects cattle, horses, sheep, and dogs)
Three tagmata= cephalon, thorax, and adbomen
Two pairs of antennae (crustaceans are the only arthropods)
Three pairs of appendages for chewing and manipulating food
vairous pairs of legs (located on abdomen and thorax)
Crustacean appendages are biramous("two-brached")
large crustacean have feathery gills for respiration
Gas exchange in smaller crustaceans occurs directly through thin regions of cuticle or through entire body
Which class of arthropod has two pairs of antennae?
Gonochoric (except barnacles)
Characteristic naupilus larva with three pairs of appendages
nauplius is evidence for single common ancestor
Decapod crustaceans include:
"Decapod" means ten feet
shrimp, lobsters, crabs, crayfish
five pairs of thoracic appendages
calcium carbonate reinforced exoskeleton
cephalothorax covered by carapace
pincers used for obtaining food
swimmerates on ventral surface of abdomen in lobsters and crayfish
Uropods are paired flattened appendages at posterior that form a paddle
Telson- tail pipe
uropods and telson push water anteriorly, propelling animal posteriorly
found on the ventral surface of abdomen in lobsters and crayfish
paired flattened appendages at posterior that form a paddle
Tail spine in decapods
____ and ___ work together to push water _____.
Uropods and telson; anteriorly
this propels the animal posteriorly
Sessile crustaceans aka...
Sessile crustaceans Barnacles:
Sessile adults, but nauplius larva is mobile
adults are filter-feeders; sweep legs through water in order to gather small food particles
Hermaphroditic condition is thought to be related to their sessile lifestyle
Have the longest penis relative to their size; allows sessile animals to cross-fertilize
_____ have the longest penis relative to their size.
Barnacles; allows sessile animals to cross fertilize.
Arthopod Class: Hexapoda aka?
largest group of animals in terms of number of species and number of individuals
found in every habitat on land and in freshwater; few found in the sea
External characteristics of insects:
Digestive tract is tube about same length as body in many
digestion occurs in stomach or midgut
trachea for gas exchange
spiracles are openings between segments along side of abdomen and thorax where air enters
In insects that feed on juices, digestive system is ____ and may be several times longer than body.
Sensory receptors of insects:
Sensory setae sensative to mechanical and chemical stimuli; numerous on antennae and legs
: thin membrane that acts like eardrum, detects sound waves and vibrations
pheromones are chemicals released by insects for communicating mating signals, trail markers, etc.
Insect life histories:
: change in form
: eggs>nymph stages>adult
: egg>larva>pupa(chrysalis)>final molt into adult or imago.
What is the difference between simple and complete metamorphosis?
Complete metamorphosis includes a pupa(chrysalis) stage.
Class myriapoda includes:
Centipedes and Millipedes
Class Myriapoda characteristics:
Both have head followed by numerous segments
both are gonochoric
all lay eggs
One pair of legs per segment
some centipedes hatch with a final number of legs; others add legs after hatching
Centipedes that do not add legs tend to do what?
Tend to care for their young, a rather uncommon behavior among invertebrates
two pairs of legs per segment
roll into flat coil or sphere for defense
glands produce foul-smelling fluid
some produce cyanide gas
This type of myriapod can produce cyanide gas
Which is the poisonous type of myriapod?
Centipedes are (carnivorous/herbivorous) but Millipedes are (carnivorous/herbivorous).
Phylum Echinodermata: The Echinoderms
development (only other phylum beside vertebrates)
Endoskeleton of calcium carbonate plates
Pentaradial symmetry (parts of 5)
water-vascular system aids in movement and feeding
larva have bilateral symmetry
What is different about echinoderm larvae?
Echioderms have pentaradial symmetry but larvae is bilateral
thought to have evolved from bilaterally symmetrical ancestors.
The oral surface of asteroids (star like), ophiiroids (snake like), and echinoids (spike like) face (away/towards) subrtrate.
Towards the substrate
The oral surface of crinoids(sea lillies) faces (towards/away) from substrate.
Away from substrate
Holothuroids have a ______ axis and oral surface that faces _____.
surface faces forward
Ossicles = calcium carbonate plates that make up endoskeleton
Depending on the class, ossicles may be more loosely arranged, tightly fit together to form a test, or scattered throughout the body.
mutable callagenous tissue can change texture from tough and rubbery to fluid in seconds if animal is disturbed.
Echinoderms can automize body parts. This means they can?
Cast off body parts
Echinoderm Water-Vascular System (WVS)
WVS extends out into each arm of a sea star
Ampulla allows tube foot to extend or contract
gas exchange occurs across body surface and the tube feet.
Holothuroidans (sea cucumbers) also have respiratory tree that branch off the hindgut, this means?
water enters through the anus
Structure on aboral(away from the mouth) surface where water enters Echinoderms
The bulb that allows tube feet in echinoderms to extend or contract
Echinoderm regeneration and reproduction:
Many echinoderms can regenerate body parts
Sexual reproduction is the norm
fertilization is external
Each class of echinoderm has a characteristic larva
These echinoderms can automize their arms
Asteroids and ophiuroids
These echinoderms can eviscerate their digestive system entirely
Holothuroidians (sea cucumber)
True or false: Some echinoderms can reproduce asexually by splitting
What are the 5 extant classes of echinodems (ACHOE)?
Orginized in parts of five or multiples of five
Arms are slender and "snake-like"
Arms join central disk very abruptly
tube feet for feeding not locomotion
brittle stars have no anus
Sea urchins and sand dollars
five double rows of tube feet extend through calcareous test (shell)
Spines are moveable and have a ball-and-socket joint
Oriented horizontally to substrate
Parts of five
Have repiratory tree
If skin is rubbed, can go from rigit to liquid in a couple minutes
Sea lilies and feather stars
oral surface faces up
What class of Echinoderm has no anus?
Ophiuroidea: Brittle Stars
Which class of echinoderm has movable spines with a ball-and-socket joint?
Class Echinoidea: sea urchins and sand dollars