Diversity of Animals I Flashcards
What is the phylum name for flatworms?
Platyhelminthes
How many germ layers do platyhelminthes have?
Triploblastic
What type of body cavity do platyhelminthes have?
Acoelomates
Describe the body cavity of platyhelminthes
Filled with loose parenchyma derived from mesoderm
Describe the symmetry of platyhelminthes
Bilateral symmetry
What is a characteristic of the platyhelminthes body shape?
Dorsoventrally flattened
What are three classes of platyhelminthes?
- Turbellaria
- Trematoda
- Cestoda
Are turbellaria free-living or parasitic?
Free-living
What structure do turbellaria use to feed?
A pharynx that comes out of a ventrally-located mouth
Describe the turbellaria diet
Carnivorous: living invertebrates or dead animals
What is an advancement of turbellaria digestive system?
Highly branched to increase surface area
Do platyhelminthes have a complete digestive tract?
No, they do not have an anus.
How does egestion occur for platyhelminthes?
Out of mouth (no anus)
Where does platyhelminthes gas exchange occur?
Diffusion through their skin (aided by being flat)
How does excreton occur for platyhelminthes?
Excretion of NH3 by diffusion
What is a huge advancement of platyhelminthes for water removal?
Water is removed by protonephridia with a flame cell.
Describe the platyhelminthes central nervous system
Transverse nerve cords with a tiny cerebral ganglia at the head of the animal.
How do turbellaria reproduce asexually?
Transverse binary fission into 2 small turbellarians called zooids.
How do turbellaria reproduce sexually? (3 steps)
- Both flatworms exchange sperm (monoecious)
- Zygotes are enclosed in a cocoon
- Zygotes develop into immature turbellarians that break out of the cocoon when the weather is good.
What is a common name for the trematoda?
Flukes
How do trematodes feed?
Adult flukes are parasitic on vertebrates
Describe the trematoda digestive tract (2 components)
- Mouth and Pharynx
2. 2 Intestinal branches
Do trematodes have a complete digestive system?
No. No anus
How does a fluke protect itself from the host’s defenses and digestive juices?
A layer of the epidermic called the tegument
Is the fluke tegument living or nonliving?
Living
Where does gas exchange occur in a trematode?
Diffusion through epidermis
Where does excretion occur in a trematode?
Diffusion of NH3 through epidermis
How does a fluke attach itself to its host? (2 ways)
- Oral sucker
2. Acetabulum (ventral sucker)
What species of trematode is the human liver fluke?
Clonorchis sinensis
Describe the eight (8) step life cycle of the human liver fluke
- Fluke eggs shed in feces of infected people and are washed into fresh water
- Fluke larva (miracidium) emerges from egg and ingested by snail
- Miracidium loses cilia to become a sporocyst
- Sporocyst grows into a redia that can reproduce asexually.
- Redia reproduces forming more rediae.
- Snail deteriorates and rediae grow tails to become cercaria.
- The cercaria attaches to fish using tail, loses tail and encysts to form a metacercaria.
- Humans eat raw fish and digestive juices release metacercaria which grows into sexually reproduce adult.
What is a definitive host?
Where the parasite produces sexually
What is intermediate host?
Where the parasite either reproduces asexually or exhibits developmental changes.
Name the five (5) different stages of the human liver fluke
- Miracidium (larva)
- Sporocyst (larva without cilia)
- Redia (can reproduce asexually)
- Cercaria (redia grows tail)
- Metacercaria (cercaria encysted in fish)
What is the common name of cestoda?
Tape worms
How do cestoda feed?
Parasitic in the intestines of vertebrates
Describe the cestoda digestive system
Cestoda secondarily lost mouth and digestive tract because the host does it for them.
How do cestoda attach to their host?
Suckers and hooks for attachment
What is the head of the tape worm called?
Scolex
What are the segments of a tape worm called?
Proglottids
Where are the tape worm’s hooks located?
On a bump of the scolex called Rostellum
Describe the maturity of the proglottids from closest to scolex to further away
- Immature
- Mature
- Gravid (filled with eggs)
How is the tape worm embryo nourished and protected?
While the egg passes through the uterus the yolk gland adds food and the shell gland adds protection.
What is the phylum name for round worms?
Nematoda
What type of body cavity do nematodes have?
Pseudocoelomates
Describe the body cavity of a pseudocoelomate
Body cavity left over from embryonic blastocoel that is not lined with peritoneum or mesenteries.
Are nematodes free living or parasitic?
Both. Many are parasitic
Do nematodes have a complete digestive tract?
Yes
What is a unidirectional digestive tract?
Food runs in one direction from mouth to anus
Why is a unidirectional digestive tract more efficient?
Regions along the tract can specialize and divide up functions
What type of symmetry to nematodes have?
Bilateral symmetry
Describe the central nervous system of nematodes
Dorsal and ventral nerve cords
Describe the nematode excretory system
Protonephridia and two lateral excretory canals.
How does gas exchange occur in nematodes?
Diffusion
How do nematodes protect themselves from host or in general?
Cuticle secreted by the epidermis
Is the roundworm cuticle living or nonliving?
Nonliving
What is the most common human roundworm parasite in the U.S. and describe them?
Enterobius vermicularis - human pinworms. Live in intestines.
What parasitic human roundworm is common in areas where the ground doesn’t freeze enough to kill the eggs and describe them?
Necator americanus - human hookworm. Burrow through skin and end up in intestines.
What parasitic human roundworm lives in uncooked pork and describe them?
Trichinella spiralis - porkworm. Encysted larvae live in the muscle tissue of pigs.
What parasitic human roundworm causes elephantitis and describe them?
Wuchereria bancrofti. Cause blockage of lymph vessels resulting in swelling.
What is the phylum name for horse-hair worms?
Nematomorpha
Where do nematomorpha live (larva and adult)?
- The larvae live in grasshoppers, crickets and cockroaches
2. Adults live in freshwater
Where are the two divisions of eucoelomates?
- Protostomia
2. Deuterostomia
What is the difference in the formation of the digestive tract between the two divisions of eucoelomates?
Protostomia: Blastopore becomes mouth.
Deuterostomia: Blastopore becomes anus
What is the difference in spindle fibers between the two divisions of eucoelomates?
Protostomia: Spindle fiber is oblique (resulting in spiral cleavage)
Deuterostomia: Spindle fiber is perpendicular or parallel (resulting in radial cleavage)
What is the difference between determinate and indeterminate cleavage?
In indeterminate cleavage, each of the four cells of the embryo can be separated and develop into a whole organism.
What is the difference between embryonic cleavage between the two divisions of eucoelomates?
Protostomia: Determinate cleavage
Deuterostomia: Indeterminate cleavage
What is a trochophore larva?
A top shaped embryo
What is a dipleurula larva?
A bilateral larva
What is the difference in embryo morphology between the two divisions of eucoelomates?
Protostomia: Trochophore larva
Deuterostomia: Dipleurula larva
What is schizocoelus?
Mesoderm splits to form the coelom
What is enterocoelus?
Coelom forms as outpockets of the gut
What is the difference in coelom formation between the two division of eucoelomates?
Protostomia: schizocoelous
Deuterostomia: enterocoelous
What phylum contains snails and octopods?
Mollusca
What is characteristic of the body design for phyla mollusca?
- Head-foot region
2. visceral mass
What is contained in the visceral mass of a mollusk?
Digestive tract, reproductive tract, circulatory system and excretory system
What helps protect the visceral mass in a mollusk?
A mantle, which often secretes a shell.
How does gas exchange for a mollusk?
Gills
What are the three (3) layers of a mollusk shell from superficial to deep?
- outer periostracum - protein (dark)
- middle prismatic layer (chalky)
- inner nacreous layer (shiny)
What are three (3) classes of phylum mollusca?
- Gastropoda
- Bivalvia
- Cephalopoda
What is torsion when referring to gastropods?
180 degree twisting of visceral mass
What is coiling when referring to gastropods
Coiling of visceral mass to allow them to secrete coiled shells
Where do thegills, anus and excretory tract of a gastropod open?
Open at the same end as the mouth as a result of torsion
What does a snail use to close its shell opening when hiding?
A tough covering on the food called the operculum
How do gastropods move?
Foot secrets mucous which they use for traction to move by cilia located on foot.
What type of circulatory system do gastropods have?
Open circulatory system
How do gastropods feed?
Scrape algae from substrate with a radula
Describe the bivalvia body form
Laterally compressed with two shells
How do bivalves attach to sediment?
protein strands called byssal threads
If bivalves are mostly sedentary, how do they become dispersed?
The larval stage allows them to disperse
Describe the dispersal of bivalvia larvae
- Eggs are released into the mantle cavity
- Sperm enter with the water current and fertilizes the egg
- Mothers host embryos in gills
- Glochidia larva leave the mother and become parasitic on fish gills
- Miniature clam falls from fish and become sedentary
What is the name of bivalvia larva?
Glochidia
What type of circulatory system do bivalvia have?
Open circulatory system
What type of feeders are bivalvia?
Filter feeders
Describe bivalvia feeding mechanism
- Incurrent siphon brings in water
- Gills trap food particles in mucous
- Particles carried to mouth
What class does the octopus belong to?
Cephalopoda
Describe the cephalopoda body plan
A large head and anterior foot is modified into tentacles used for walking, catching prey and mating.
Describe the shell of a cuttlefish
Small internal shell
Describe the shell of a squid
Small internal “pen”
Describe the shell of an octopus
no shell
Describe the shell of a nautilus
Full, chambered shell
What do cephalopods feed on?
Other animals (small invertebrates to young sperm whales)
What type of circulatory system do cephalopods have?
Closed circulatory system
Describe octopus nervous system
Have a memory and ability to learn. Large neurons that are used for neurological research.
Describe the octopus eyes
Octopus see images, shapes and colors
What is the relationship between cephalopod eyes and vertebrate eyes?
Convergent evolution - evolved separately but greatly resemble each other.
What cells allow cephalopods to change colors?
Chromatophores
What response allows cephalopods to escape from predators by disrupting their sight and smell?
Dark fluid secreted by ink glands
What is the phylum name for segmented words?
Annelida
What are each segment of a segmented worm called?
Metameres
What is the term for body forms composed of repeated segments?
Metamerism
What separates each metamere internally?
Septa
What type of circulatory system do annelids have?
closed circulatory system
What two (2) blood vessels do annelids have?
- Dorsal blood vessel
2. Ventral blood vessel
What organs comprise the annelid circulatory system? (two types of organs)
- two blood vessels
2. five hearts
Describe the annelid excretory system
Metanephridia remove excess wastes from body cavity and the blood
Describe the annelid nervous system (3 components)
- Large neurons in head called cerebral ganglia
- Ventral nerve cord
- Branches in each segment called ganglia
What are the three classes of annelids?
- Polychaeta
- Oligochaeta
- Hirudinea
What is the largest class of annelids?
Polychaeta
Describe the polychaeta body structure
Polychaetes have a pair of parapodia on every segment and hair-like setae on every parapodia
Where does gas exchange occur in a polychaeta?
Notopodium: thin part of parapodium
What polychaete sensory organ are located on each segment?
Neuropodium: part of parapodium
What structure do polychaetes use for locomotion?
Parapodia
What two polychaete sensory organs are located on the head?
- Eyes
2. sensory palps
What is the region of the polychaete that surrounds the mouth?
peristomium
What is the region of the polychaete that is in front of the mouth?
prostomium
What are two ways polychaetes feed?
- Protrusible pharynx with teeth used to feed on small, invertebrate prey
- Tentacles used for filter feeding
How do polychaetes reproduce asexually?
Budding
How do polychaetes reproduce sexually?
Polychaete grows into a worm with two distinct segments: asexual atoke and sexual epitoke. The epitoke breaks free and goes to the surface of the water to breed.
Describe the body structure of oligochaetes
Setae that run down the sides of segmented body
What is the anterior tip of the oligochaete called?
prostomium
What do oligochates feed on?
Scavengers that feed on decaying vegetation
How does gas exchange work for oligochaetes?
exchange gases across their moist skin
Why is oligochaete distribution limited to water or moist soil?
they need moisture for gas exchange
How do oligochaetes reproduce sexually? (4 steps)
- Two worms line up in opposite directions
- Exchange sperm
- Deposit the eggs into a cocoon of mucous secreted by clitellum
- Young worms hatch from the cocoons
What is class that contains leeches?
Hirudinea
Describe hirduinea body structure (2 components)
- 34 segments and additional rings called annuli
- anterior and posterior sucker
- No setae or parapodia
What do leeches feed on?
Some feed on body fluids or entire body of invertebrates. Others feed on vertebrate blood.
How do leeches feed on their host?
Mouth is located in center of anterior sucker and contains three “teeth” that slice through tissue.
How do leeches prevent host blood from clotting?
They secrete an anticoagulant called hirudin
How do leeches get the host’s blood into their digestive tract?
Muscular pharynx pumps the blood into their digestive tract
How does gas exchange occur in leeches?
Gases diffuse across their moist bodies
Describe the movement by annelids onto land
- Polychaetes are most primitive annelids and are all marine.
- Oligochaetes invaded freshwater and evolved into oligochaetes and hirudinea
- Oligochaetes moved into moist, terrestrial ecosystems and evolved into arthropods.
What is the phylum for animals with jointed legs?
Arthropoda
What is a characteristic of arthropods that relates them to annelids?
external metamerism (septa are missing internally)
Describe arthropod nervous system
Ventral nerve cord
What are three (3) functions of the arthropod exoskeleton?
- Support
- Muscle attachment
- Prevent dehydration
What molecule composes the exoskeleton of arthropods?
Chitin
What is tagmatization?
Metameres of the body have been organized into functional body regions
What are three body regions of insects?
Head, thorax and abdomen.
What is the body region containing the head, feeding structures and walking legs for crayfish?
Cephalothorax
What development gives arthropods excellent strength and speed?
Well-developed striated muscles
What kind of circulatory system do arthropods have?
Open circulatory system
What is an advantage of arthropod metamorphosis?
Larva and adult differ in feeding requirements and reduce competition.
What is the largest of all animal phyla and what percent of all animals does it include?
75% of all animals are arthropods
What was the first animal phylum to dominate the terrestrial ecosystem?
Arthropoda
What are four (4) subphyla in the phylum arthropoda?
- Trilobita
- Chelicerata
- Crustacea
- Uniramia
What is significant about the subphylum trilobita?
It is extinct and looks like Kabuto from pokemon.
What animals are included in subphylum chelicerata?
Spiders, horseshoe crabs, scorpions, ticks, mites, sea spiders
What body regions are present in sub phylum chelicerata?
Cephalothorax and abdomen
What appendages aid in feeding for chelicerata?
First pair of appendages are called chelicerae and aid in feeding
What body regions are present in subphylum crustacea?
Cephalothorax and abdomen
What is characteristic of crustacean antennae?
Two pairs of antenanae and one pair is biramous
What is a uniramous limb?
Consists of a single series of attachments connected end-to-end
What is a biramous limb?
A limb that branches into two and each branch consists of segments attached end-to-end
What type of limbs do crustaceans have?
Biramous
What animals are included in subphylum crustacea?
Brine shrimp, lobsters, crabs, crayfish, copepods and barnacles
How many pairs of antennae do animals in subphylum uniramia have?
One pair of antennae
What type of limbs do subphylum uniramia have?
Uniramous appendages
What are three classes in the subphylum uniramia?
- Diplopoda
- Chilopoda
- Insecta
How many legs do diplopoda have?
2 pairs of legs per segment
What do millipedes look like in cross section?
Round body
How many legs do chilopoda have?
1 pair of legs per segment
What do centipedes look like in cross section?
Oval body
What do diplopoda (millipedes) feed on?
Decaying plant litter
What do chilopoda (centipedes) feed on?
Earthworms, snails, insects etc.
What part of a centipede should you be careful of?
The front legs contain toxins that are painful but generally harmless
How many legs do insects have
3 pairs (6 total)
What phyla are considered protostomes?
Mollusca, Annelida, Arthropoda
What phylum is the most primitive deuterostomes?
Echinodermata
What kind of symmetry do echinoderms possess?
Pentaradial symmetry
What does a sea star use for support?
Endoskeleton made of calcium carbonate plates and ossicles covered by epidermis
What is the flow of water in a sea star? (5 steps)
- Madreporite
- Stone canal
- Ring canal
- Radial canal
- Tube feet
What side of the sea star is the mouth located?
Ventral
What type of digestive tract do echinoderms have?
Complete
What are five classes of echinoderms?
- Asteroidea
- Ophiuroidea
- Echinoidea
- Holothuroidea
- Crinoidea
What animals are included in asteroidea
Sea stars (arms in multiples of five)
What animals are included in ophiuroidea
Brittle stars and basket stars
Describe the arms of brittle stars
Unbranched, long and thin
Describe the arms of basket stars
Branched, long and thin
What animals are included in echinoidea
Sand dollars and sea urchins
Describe the morphology of sea urchins
Round and spiny
Describe the morphology of sand dollars
flattened
What animals are included in holothuroidea
sea cucumbers
Describe sea cucumbers (2 components)
Elongate and sluggish burrowers
What animals are included in crinoidea
Sea lilies and feather stars
Describe the life style of crinoidea
Sedentary
What is the most primitive class of echinodermata?
Crinoidea
What are four characteristics of phylum chordata?
- Notochord
- Pharyngeal gill slits
- Dorsal tubular nerve cord
- Post-anal tail
What is a notochord?
A flexible support rod made of connective tissue
What are pharyngeal gill slits?
Openings in the pharyngeal region of the digestive tract to the outside of the body
What is the purpose of pharyngeal slits? (lower animals and higher animals)
Lower chordates: Used for filter feeding and gas exchange in lower chordates
Higher chordates: Only present in the embryo
What is a dorsal tubular nerve cord?
Nerve cord dorsal to notochord. Enlarges to form brain and constitutes the central nervous system
What are three subphyla of chordates?
- Urochordata
- Cephalochordata
- Vertebrata
What animals are included in urochordata?
Tunicates
Describe the anatomy of larval tunicates
Only the free-swimming larva contain notochord and nerve cord
When are notochord and nerve cord present in cephalochordata?
Notochord and nerve cord are present throughout their life
What two classes of chordata are considered invertebrates?
Urochordates and cephalochordates
What is characteristic of subphylum vertebrata?
Bony or cartilaginous vertebrae protect nerve cord
When is notochord present in vertebrata?
Only in the embryo
What kind of skeleton do vertebrata have?
Endoskeleton
What are the advantages of an endoskeleton?
Allows much larger body seize with a lighter skeleton
Describe the pharynx of vertebrates
Very muscular
What is the purpose of the pharynx in many vertebrates?
Used to draw water over gills
Describe the nervous system of vertebrates
Highly advanced with dorsal nerve cord and brain
Describe the limbs of vertebrates
Paired limbs
Where do fishes live?
Aquatic their entire life
What is the relationship between fish and all aquatic and terrestrial vertebrates?
Ancestors to all aquatic and terrestrial vertebrates
What were the first animals to have jaws?
Fish
What were the first animals to have a reduce number of appendages?
Fish
What is significant about fish blood?
First animals to have red blood cells containing hemoglobin
Describe the anatomy of a fish heart
2-chambered heart with 1 atrium and 1 ventricle
How many circuits are in the fish circulatory system?
One circuit
Describe countercurrent flow
Water and blood flow in opposite directions so that the water that has been most depleted of oxygen will line up with the blood that has just begun diffusion
What is the advantage of countercurrent flow
The countercurrent system transfers 80-90% of the oxygen in water to blood vs. 50% of water in a same-current flow
What superclass of fish were the earliest vertebrates?
Superclass agnatha (“without jaws”)
What are two classes in the superclass agnatha?
- Myxini
2. Cephalaspidomorphi
What animal is representative of class Myxini?
Hagfish
What animal is representative of class cephalaspidomorphi?
Lamprey
Describe the body shape of Hagfish (4 components)
(1) Scaleless (2) eel-like body with (3) no dorsal fin and (4) no paired appendages
Describe the skeleton of hagfish
Cartilaginous endoskeleton
What is significant about hagfish eyes?
Degenerate eyes make them effectively blind
What do hagfish eat?
Scavage on dead or dying animals (not parasitic)
What is an indication that hagfish are adapted to seawater environment?
body fluids are isotonic with seawater
What is a the characteristic protective mechanism for hagfish?
Covered in slimy mucous
Describe the body shape of Lamprey
(1) scaleless (2) eel-like body with (3) a dorsal fin and (4) no paired appendages
Describe the skeleton of lampreys
Cartilaginous endoskeleton
What is an indication that lampreys are adapted to freshwater environment?
Body fluids are hypotonic to salt water
Describe lamprey eyesight
Well-developed eyes
Are lampreys free-living or parasitic?
Both, many are parasitic
What superclass of vertebrates have jaws?
Gnathostoma
What are two classes in the superclass gnathostoma?
- Chondricthyes
2. Osteichthys
What animals are in the class chondricthyes?
Sharks, skates and rays (cartilaginous jawed fishes)
Describe the tail of chondricthyes
Heterocercal tail (asymmetrical bones)
Where is the mouth located on chondricthyes?
Ventrally located below snout
What kind of scales do sharks have?
Placoid scales
What kind of skeleton do chondricthyes have?
Cartilaginous endoskeleton
Why must sharks keep swimming to stay afloat?
They lack a swim bladder to aid buoyancy
What is a big advancement in the chondricthyes for their sexual reproduction?
Internal fertilization
What is it called when an animal lays a fertilized egg?
Oviparous
What is it called when an animal gives life birth?
Viviparous
What is it called when an animal retains eggs inside their body until hatching and then seemingly gives a live birth?
Ovoviviparous
In viviparous animals what nourishes the embryo?
Mother’s placenta
In oviparous animals what nourishes the embryo?
yolk of the egg
Where does gas exchange occur for chondricthyes?
External gill slits
Describe the skeleton of osteicthys
Bony endoskeleton
Describe the tails of osteicthys
Homocercal tails (symmetrical)
What three (3) types of cells do osteicthys have?
- Ctenoid (silent c)
- Cycloid
- Ganoid
Where is the mouth located on osteicthys?
Terminal mouth
What covers the gills of a bony fish?
Operculum
What type of fertilization occurs in most bony fish?
External fertilization
What are tetrapods?
Four limbed animals
What two (2) fish most closely resembles tetrapods?
- Lung fish
2. Lobe-finned Fish
When did tetrapods arise?
During the Devonian period in response to the drying of freshwater lakes
What is significant about lung fish and lobe-finned fish mechanism of gas exchange?
Primitive lung made from a swim bladder absorbs oxygen and removes waste.
What is significant about lung fish and lobe-finned fish circulatory system?
Double circulatory system
What is significant about lobe-finned fish fins?
Well-developed fins allow them to crawl across land