chapter 21 Invertebrates Flashcards
How many known animals species are there?
1.3 million
What specific set of features do all animals have in common?
They have eukaryotic cells that lack cell walls
Their cells produce an extracellular matrix
They have multicellular bodies
They go through a blastula stage of development
They are heterotrophic
What is a blatula?
a sphere of cells surrounding a fluid-filled cavity
How many animal phyla are there?
nine
Name all the animal phyla
Porifera, Cnidaria, Platyhelminthes, Mollusca, Annelida, Nematoda, Arthropoda, Echinodermata, Chorodata
Are most animals vertebrates or invertebrates?
Invertebrates
What are invertebrates?
animals that lack backbones
What are vertebrates?
animals that have backbones
Which phylum have vertebrates?
Chordata
Where did life begin?
in water
How many million years ago did the first animals arise?
570 million years ago
Ancient animals probably resembled what aquatic protist?
choanoflagellates
do animal features reflect shared ancestry?
yes
How are animals grouped?
by shared features of body form, developmental characteristics, and DNA
The first branching point in animal taxonomy distinguishes…?
animals having tissues or not
what are eumetozoans?
animals with true body tissues
What are parzoans?
animals with no true body tissues
What does the second branching point distinguish?
symmetry and embryonic germ layers (2 vs 3)
a body form in which multiple similar parts are arranged around a central axis
radial symmetry
Do most eumetazoan phyla have radial symmetry or bilateral symmetry?
bilateral
What do bilaterally symmetric animals have that others don’t?
a head and a tail
define cephalization
the tendency to concentrate sensory cell and a brain at the animal’s head. Typically this is accompanied by greater sensory complexity
do most eumetazoam phyla have 2 germ layers or 3?
3
How is the gastrula formed
by the blastula folding on into itself
What is a blastula?
an embryonic ball of cells
What is a cup-shaped structure composed of two or three layers of tissue
gastrula
Name the 3 germ layers developed by the gastrula
Endoderm, ectoderm, and mesoderm
What does the ectoderm develop?
the skin and nervous system
What does the endoderm develop?
the digestive tract
What does the mesoderm develop?
the muscles and circulatory system
The third branching point distinguishes animals by…?
how their gastrula develops
what is a protostome
“mouth first”
If the first indention of the gastrula develops into the mouth
The anus will develop from the second opening
What is a deuterostome?
“anus first”
If the first indention of the gastrula develops into the anus
the mouth will develop from the second opening
What is a coelom?
a body cavity surrounded on all sides by mesoderm
Where do internal organs grow?
in the coelom
What is a pseudocoelom
a cavity that is lined partly with mesoderm and partly with endoderm
What does it mean when an animal doesn’t have a coelom?
they lack a body cavity
Animals that have a mouth that both takes in food and ejects wastes have…?
an incomplete digestive tract
Animals have a {blank} if food passes in one direction from mouth to anus
complete digestive tract
The division of an animal body into repeated parts is…?
segmentation
What advantage to segmented bodies have over unsegmented bodies?
segmented bodies are more flexible and have more potential for developing specialized body parts than unsegmented bodies
what is direct development?
animals that resemble adults in their juvenile stage
What is indirect development?
Animals that have a larval stage that does not resemble the adult form
What does an animal with indirect development do as it matures into an adult
the larva undergoes metamorphosis
Porifera
Sponges aquatic and sessile no true tissues hollow bodies asymmetric or radially symmetric
sessile
anchored to a surface
how to sponges eat
filter feeder
water moves into a sponge’s body through pores in its sides, then out through a hole at the top. This allows the sponge to trap food and eliminate waste
What are collar cells
cells that sponges have to trap food and start to digest it
what are amoebocytes?
cells that sponges have to digest food and distribute it to other parts of the body
True or false
sponges are hermaphrodites
true
Do sponges reproduce sexually or asexually?
both
How do sponges reproduce asexually?
by budding
how do sponges reproduce sexually
sperm is released into the water and fertilize eggs retained in the body of the sponge
Cnidarians
Symmetry?
Germ layer amount?
simple eumetazoans
aquatic, radially symmetric, 2 germ layers
Name the 4 groups of cnidarians
Jellyfish, hydra, coral, and sea anemones
what is the unique feature found in cnidarians’?
mesoglea: a jellylike, noncellular substance found between the 2 cell layers that make up a cnidarian’s body
What are cnidocytes?
cells resembling tiny sharp harpoons used to sting predeators or prey
found in cnidarians
The sting can irritate, paralyze, or kill other animals
Can cnidarians reproduce sexually or asexually?
both
How do cnidarians reproduce?
Adults release sperm or eggs into the water. When they meet up fertilization occurs to form a zygote. The zygote develops into a larva and then a polyp, which can form a colony and release new medusae
What is a polyp?
a sessile cnidarian
Are flatworm protostomes?
yes
Platyhelmithes
Symmetry?
Germ layers?
flatworms
bilaterally symmetric
3 germ layers
3 groups of flatworms
Planarians, flukes, and tapeworms
do flatworms have a coelom?
no
what are the advantages of not having a coelom?
the flat body shape increases surface area and allows for effiecient gas exchange
do flatworms have a specialized respiratory and circulatory system?
no
What do planarians use to eat?
Pharynx: a feeding structure that brings food into the body and excretes undigested food
the nervous system of planarians
a brain and nerve cords
It can sense touch, chemicals, and light
Are flukes and tapeworms parasitic?
yes
mollusks
soft unsegemented protosomes
large diverse phylum
a true coelom
features of a mollusk
a mantle, muscular foot, visceral mass, radula
Mantle
a fold of tissue that secretes a calcium carbonate shell in mollusks
what is a muscular foot used for?
locomotion
what is a visceral mass
a region of a mollusk’s body where organs are found
what is a radula
a tougue-like strap with teeth made of chitin
Used for feeding
the 4 groups of mollusks
Chitons, bivalves, gastropods, cephalopods
mollusk group that have eight overlapping shells
chitons
mollusk group with hinged shells
bivalves
mollusk group with spiral shells
gastropods
mollusk group with internal or absent shells
cephalopods
Do all mollusks have an open cirulatory system and reproduce sexually?
yes
Which of the mollusk groups have a well-developed nervous system
cephalopods
large brain, eyes, excellent sense of touch, and impressive problem-solving abilities
Do mollusks have a complete digestive tract or an incomplete digestive tract?
complete
Annelids
segmented worms
Each body segment functions the same as the others
Do annelids live in different environments?
yes
Earthworms
annelid that lives in soil and are crucial for keeping it aerated
Leeches
annelids that live in freshwater. They drink blood and eat small animals
Polychaetes
annelids
marine worms
the 3 groups of annelids
earthworms, leeches, and polychaetes
annelid organ systems
complete digestive system, closed circulatory system with aortic arches, and a nervous system that includes a brain and ventral nerve cord
each body segment contains excretory organs
what is the saddle-like thickening area on earthworms for?
to hold eggs in a specialized cocoon
Nematoda
unsegmented worms
roundworms
closest evolutionary relatives of roundworms are…?
arthropods
do roundworms cause disease?
some
parasitic roundworms such as pinworms, heartworms, and hookworms infect the intestines, muscles, blood, and lungs of humans and other animals
nematodes organ systems
few organ systems
includes a brain and nerve cords.
Do roundworms have specialized circulatory and respiratory organs
no
a fluid in the pseudocoelom distributes nutrients, oxygen, and carbon dioxide
do nematodes have a coelom, pseudocoelom, or no coelom?
pseudocoelom
Arthropods
largest most diverse phylum of animals. Their legs, antennae, mouthparts, and other organs are joined
name the 5 arthropod groups
Trilobites, chelicerates, myriapods, crustaceans, insects
do all arthropods have an exoskeleton?
yes
made of chitin
supports and protects the body
what happens as an arthropod’s body grows
they molt and grow a new exoskeleton
specialized body segments in arthropods
head, thorax, and abdomen. Segments in each region develop specialized functions
organ systems of arthropods
a respiratory system made up of holes called spiracles for letting in air, and tubes called tracheae and book lungs for gas exchange
well developed nervous system, open circulatory system, and complete digestive system
Trilobites
extinct marine phylum of arthropods
chelicerates
subphyla of arthropods
grasping clawlike mouthparts
(spiders)
how are arthropods grouped?
by their mouthparts
mandibulates
subphyla of arthropods
chewing, jawlike mouthparts
(ant mandibles)
horseshoe crabs, mites, ticks, spiders, and scorpions are…?
chelicerates
Myriapods make up one group of …
mandibulates
The heads have jaws and antennae; the rest of the body has pairs of legs
Crustaceans make up another group of…
mandibulates
crabs, shrimp, and lobsters are…
crustaceans
all have two pair of antennae
Insects are another group of …
mandibulates
There are million of [blank] species. They each have one pair of antennae, six legs, and (usually) two pairs of wings
insects
Echinoderms
marine deuterostomes
closely related to chordates
sea urchins, sea stars, and sea cucumbers are …
echinoderms
do echinoderms have radial or bilateral symmetry?
radial as adults
as larve, they are bilateral
pentamerism
5-part radial symmetry
special features of echinoderms
regeneration and tissues that switch between soft and hard
water vascular system
tube feet
water vascular system
a series of enclosed, water-filled canals that end in hollow tube feet
versatile, fulfilling the functions of a complex circulatory, respiratory, and excretory system
what do echinoderm tube feed do?
pump out water and act as locomotion and sensory systems
