Post-midterm Flashcards
What are the trematoda? How do they differ from other platyhelminths
Flukes and digeneans. Differ because they can undergo asexual reproduction. Have diverticulated gut, specialized genital organs
Describe the external features of the trematoda
Have two suckers: oral and ventral - both used to attach to host. Many can absorb nutrients directly into their bodies.
What purpose does the pharynx of digenean trematodes serve? Describe the gut
Muscularized, acts like a pump to suck food material into mouth to gut. Gut can be either simple or highly diverticulated, helps to actively ingest host tissues
Trematodes are typically differentiated by _______
Vitellaria or yolk glands
What purpose does the glycocalyx and tegument of trematodes serve? What is their composition?
Purpose is to resist the digestive enzymes of host.
Tegument is outside the body and is a multinucleated mass.
Briefly describe the generalized digenean trematode lifecyle?
Egg (usually expelled in feces) -> miracidium larva (ciliated larval form that enters a snail then loses ciliaand becomes a..) -> Sporocyst (asexually reproducing clusters of cells which become…) -> Redia (with oral sucker, pair of protonephridia, simple branched gut) -> Metacercaria (basically advanced larvae that encyst themselves then become..) -> Cercaria (leave snail through body wall or gills) -> adult
The cestodes are otherwise known as the _____
tape worms
Briefly describe the anatomy of cestodes
Divided into small sections called “proglottids”, usually have a reduced nervous system and no gut. Have small spines called “microtriches” along the tegument. On one end of the organism is an area called the scolex, which is covered in suckers and anchoring hooks to attach to intestine of host
Describe the reproductive structures found in a Cestode proglottid
Have a genital pore with a cirrus (penis) as well as paired reproductive structures. The male system matures sooner than the female system (so self fertilization is rare). Always contained a vitelline gland.
A _____ proglottid is one that is full of eggs
Gravid
Describe the health problems caused by the fish-human tapeworm
Intermediate host is fish, definitive host is mammals. They take up B12 so quickly that they can cause death
How does tapeworm grow in the intermediate host and transfer to humans?
Ingested, grows in intestine and often pass in feces.
In the intermediate host, the juvenile grows in the muscle of the organism. Thats why it transfers to human mouthparts
What do dog tapeworms do to humans?
Usually they infect the liver, but can infect any organ. Sometimes, it can infect the brain, where it produces scolexes that become large cysts and do not die down
What are the cysts caused by dog tapeworms called? Describe them
Hydatid cysts. Can grow extremely large (golf ball size), Usually the pathology depends on cyst size and location. Single liver cyst could prove fatal.
Cysts are organized by having a thick outer layer, several thinner internal layers, and a bunch of protoscolices.
How are the molluscs related to the annelids?
Share common larval form called the “trochophore larva”.
What are the major groups of molluscs
Gastropods, bivalves, cephalopods
What are the characteristics that all molluscs share?
Bilateral symmetry, triploblastic/3 tissue layers, unsegmented, eucoelomate, soft bodied (composed of head, foot, visceral mass), mantle secretes shell, respiration occurs by gills/ctenidia
Why are gastropods called what they are?
Called such because the gastric pouch is above the foot
Gill structures of molluscs are called ____
Ctenidia
Briefly describe the circulatory systems of the mollusc groups
Gastropods and bivalves use low-rate ciliary currents with a counter current exchange systems.
Cephalopods require more quick blood flow, since they move more quickly and have a fluid skeleton
Describe the respiration of the different mollusc groups
Gills or ctenidia are located in the mantle cavity. May have between 0 and two gills. Land forms often used mantle wall as a lung.
Ctenidia are irrigated by ciliary movements in the mantle cavity, use counter current exchange.
Describe the gill structures of molluscs
Lobes sticking out from a central axis with afferent and efferent blood vessels running through it. Skeletal rods support the filaments, and water runs along the gill filaments
Describe the digestive system of molluscs?
May be straight, u-shaped, or coiled. Begins at the mouth and ends at the anus, which empties into the mantle cavity (mantle current helps remove wastes). Mouth is characterized by a radula, and a muscular tongue that pushes it out of the mouth. Stomach is called a protostyle, which is a rotating cone of mucous that sorts large food particles from small food particles. Grooves and folds lead to opening of the digestive glands.
The membrane on top of the radula is made of _____
chitin
Describe the basic diets of molluscs
Many Gastropods are grazers, scraping plant/animal material off the ground. Bivalves typically filter feed (or may be detritovores), and cephalopods use a beak to tear apart prey
Describe the mollusc circulatory system
Have muscular heart composed of muscular ventricle which pumps into aorta then branched aorta then empty into sinuses. Nephridia pick up blood from there and then filtration occurs
Why is the heart of cephalopods unique?
Double chambered heart
Describe the excretory system of molluscs
Consists of 1 or 2 pairs of metanephridia (open at both ends) which open from the floor of pericardium and empty into the mantle cavity
Describe the nervous system of molluscs
Have ring of nervous tissue around esophagus, connected to bundles of nerve fibres, with many many branches. Changes based on lifestyle (ex. cephalopods have highly complex eyes, whereas bivalves have no eyes)
Describe the sense organs that molluscs possess
Statocysts for balance, tangoreceptors for touch/pressure, chemoreceptors for measuring silt levels, eyes.
Describe the reproductive systems of molluscs
Usually dioecious. Some, such as slugs and land snails are hermaphroditic. Gonads release gametes by rupture. Gonads are frequently reduced to a single one. Fertilization usually external.
Describe the larvae of molluscs
First larvae is a trochophore, which is free swimming in all but the cephalopods (then it is a egg). In bivalves and gastropods it metamorphoses into veliger. Veliger has 2 ciliated flaps for swimming and feeding.
Clams have no larvae.
How does the gastropod mantle become so twisted? Describe the external anatomy of it
Mantle on one side is more active than on the other side, resulting in spiral shape. Usually spirally-coiled either dextrally or sinistrally, secreted by edge of the mantle.
Describe the typical gastropod shell?
Composed of outer periostracum, middle prismatic layer (CaCO3), and inner nacreous layer. Formation of shell begins in larval stage as the “protoconch” and it forms the tip of the whorl throughout life. The rest of the shell is uniform in structure and is laid by the edge of the mantle over time, resulting in a spiralled tube through the shell wrapping around columellae.
The _____ forms the point of attachment for the retractor muscles in gastropods. What is the purpose of these muscles?
Columella. Retractor muscles function to pull head-foot complex into the aperture of the last coil of the shell. There may be an operculum to help close the shell
Why is the anus/mantle cavity opening of gastropods over the mouth?
Because if it was behind the mouth and foot, water wouldn’t’ be able to enter the mantle cavity when the shell is closed
How do soft bodied gastropods protect themselves?
They often store nematocysts from coral polyps - incorporating cnidarian tissues into theirs. Toxins are also secreted from the top of the body.
Briefly describe class bivalvia
All aquatic, most marine. Have a bivalved shell hinged at the dorsal surface. Allows protrusion of foot (For locomotion) and siphons (for respiration/feeding). Can be sedentary or motile.
How do clams move?
Protrude foot from body, attach it to substrate, and contract muscles to pull it forward
The _____ muscle stretches the hinge ligament of Bivalves
adductor
In bivalves, the head is modified as what? What purpose does this serve?
Labial palps which function to increase surface area for filter feeding
How do bivalves feed? how is the foot represented across different groups?
Almost all are filter feeders (use gills to filter), but some are deposit feeders.
Foot is reduced in sedentary forms and scallops
How/when do bivalves move?
Move when threatened.
How do bivalves fertilize?
Almost all fertilize externally
Describe the shell of various cephalopods
Shell reduced in all but the primitive Nautilus. Completely absent in Octopi
Why are cephalopods called what they are?
Because the head and foot are closely associated, with extensions of the foot forming the tentacles and arms, and the head immediately above it. The rest of the body is found behind the head and foot
How do cephalopods move?
Via propulsion, pushing water out of the body using contraction of the mantle. They are extremely active
What is the name of the gas vesicle Nautilus sp. use to rise up through water
Siphuncle
How are the greater respiratory demands of cephalopods met?
Have a respiratory pigment called hemocynin that operates like hemoglobin, as well as accessory hearts associated with each gill. Called branchial hearts (muscles used to stimulate blood flow)
Describe the cephalopod nervous system
Very complex eyes, which are focused by moving the lens. Brain is super complex and they have the capacity for learning.
How do cephalopods eat and digest?
Prey are handled by arms and tentacles (suckers). Tear prey apart using hard beak,food retrieved by radula. Stomach is sac like and produces concentrated gut secretions to help with active lifestyle. Wastes expelled through anus in mantlecavity
Where does cephalopod ink come from?
Anus
Briefly describe cephalopod reproduction
Have single gonad, sperm usually transferred directly into female mantle cavity (internal fertilization). Eggs encapsulated and either allowed to float free or adherign to substrate
NO LARVAL FORM
Annelids are ______, meaning they have a true body cavity
Coelomate
The segmented nature of the annelids is otherwise referred to as _____
metamerism
Briefly describe the annelids
Have at least one pair of setae, are segmented, thin epidermis (can be covered by cuticle) for gas exchange and excretion
How do annelids locomote?
Crawling, burrowing, or swimming
Describe the general anatomy of an annelid segment
Each body segment has its own metanephridia, wrapped by blood vessels, with a nephridial pore opening into the environment. Gut is u-shaped to increase surface area and runs the length of the body
What adaptations do leeches have for their blood feeding lifestyle?
Sharp chitinous elements in the mouth. Saliva contains “hirudin”, used as an anti-coagulant. Elastic gut with increased storage capacity for blood or absorption.
Describe earthworm locomotion
Expand and contract body segments peristaltically .
What is the difference between the general body shape of oligochaetes and hirudinea?
Oligochates cylindrical, leeches dorsoventrally flattened
Which of the annelids have clitella?
Oligochaetes
How do polychaetes differ from oligochaetes. How do they locomote?
Basically the same, but they have parapodia (similar to legs) for respiration or locomotion. They have a large amount of setae (far more than oligochaetes). Filter/deposit feeders, live in/out of burrows.
They locomote via alternate contraction of longitudinal muscles.
Describe some of the different feeding modes of the polychaetes
Some are sedentary, living in burrows and deposit feeding using mucous covered tentacles. Some have evertable pharynxes that can be used to swallow large prey the way snakes do. Others still are suspension or filter feeders using tentacles or ciliary grooves.
Describe the modified body plan of the “tube worm”.
Have fans to pump water in and a large mucous bag to trap material (acts as filter). Modified parapodia below that will create a ventilating current and push feces away
Describe reproduction in annelids
Oligochaetes and leeches are hermaphroditic, but oligochaetes and reproduce sexually and asexually AND regenerate missing parts.
Polychaetes have two sexes and transform into reproductive individuals referred to as “epitokes”.
How do polychaete “epitokes” differ from “atokes”?
Epitokes have bigger eyes, locomote, swim to the surface of the water. Females can be bioluminescent. Reproductive sections can disintegrate after reproduction.
Describe the clitellum of annelids
Clitellum forms when organism is ready to reproduce. Body becomes more cuboidal and secretes mucous. The penis is stabbed into the clitellum.
After fertilization, the clitellum forms a mucousy cocoon for the juvenile (direct development).
What are the aschelminthes? What groups are members of the aschelminthes?
A phylum grouping with no common ancestor that can live in marine or fresh water, are tiny worm shaped animals, have few somatic cells that reach “Eutely”, a point in development where they stop dividing and simply grow bigger forever. Aschelminthes have no TRUE coelom or circulatory system. Usually have adhesive organs in epidermis to adhere to a substrate.
Includes Rotifera, Nematomorpha, Nematoda, Acanthocephala and sometimes Tardigrada
What are the features common to Rotifera?
Most freshwater, solitary and free swimming. Some sessile or colonial. Have a fixed number of somatic cells. Body composed of trunk and foot, anterior with corona or ciliated tufts for feeding/swimming. Eyes may bepresent and trunk may have armour called lorica.
Describe the foot of the rotifers
Often divided into 1 or more toes with attachment organs. Can move by creeping over substrate
Describe food handling and digestion in rotifers
Ventral mouth surrounded by corona of cilia. Food drawn into mouth via ciliary currents, where “trophi” (tooth-like projections) grind food in the enlarged “mastax” of the esophagus.
Carnivorous rotifers may capture prey then close up corona like a venus fly trap
Do rotifers have a nervous system? Do they have kidney-like structures?
Yes, also have eyespots for light detection. Have protonephridia for water balance.
How do rotifers survive harsh inland fresh-water winters?
Undergo “Cryptobiosis”, where the rotifer will secrete mucous in fall and metabolic activity lowers until it the organism encysts itself and becomes dormant
Describe the “acanthocephala”
Parasites in the internal organs of vertebrates, usually requiring 2 hosts in life cycle (juvenile usually found in crustaceans). Composed of spiny proboscis and longer trunk. Usually a few mm long. Have no gut and absorb food material through the epidermis.
Describe reproduction and egg development in acanthocephala
Internal fertilization results in “acanthor” larva in a capsule/shell. Egg leaves host body in feces. Egg is usually consumed by an insect then encysts as a cystacanth in the hemocoel
Describe how acanthocephalan larvae may change the behaviour of hosts to enhance transmission
Ex. an acanthocephalan larvae causes Gammarus, a small crustacean, to swim to the surface of water where it is more likely to be eaten by ducks
Describe the “nematoda”
Very diverse (almost as diverse as beetles). Can be free living or parasitic (on animals or plants). Are aquatic but can be found terrestrially in soil water. They are round, long, and thin. Very small and have a thick multilayered cuticle (molted regularly) - can absorb nutrientsthrough epidermis. Have a tubular gut and cutting/piercing structures on the mouth. Buccal cavity may be armed with teeth.
Describe the human pinworm
Lives near the anus of children, causes itching sensation. It is super common and not very harmful.
How do nematodes locomote?
Have no circular muscles and therefore undulate using long muscles contracting against hydroskeleton
What is unique about the body fluid of nematodes?
Body fluid (hemolymph) is under extreme pressure and flattens gut when not in use.
The _____ drives food back into the intestine of nematodes
Pharyngeal bulb
How do nematodes osmoregulate
Via excretory cells that empty into canals. Wastes excreted across body surface
Describe fertilization in nematodes
Sperm lack flagella and move by amoeboid locomotion. Fertilization occurs in the lower reproductive tract of the female and egg formation occurs in upper uterus
how do male and female nematodes differ in appearance?
Males have hook at the end of their tail for holding female during reproduction. Also have a gonopore with a “spicule” for opening the female gonopore.
Females are bigger and the gonopore is further anterior
Describe the nematode condition “Elephantiasis”
Larvae transmitted by mosquitos, live in lymph glands/vessels. Immune response causes the accumulation of body fluid.
Describe the nematode condition “Trichinella”
Spread when people eat undercooked or raw pork. Juveniles burrow into a single muscle cell in the pig, inducing cyst formation/ Can sit dormant for weeks to years. The third juvenile stage (J3) is the one that infects humans.
Describe the nematode condition “Dracunculiasis”
Infected by drinking water. Adult worms live in human sub-dermal tissue. To get rid of the infection, people will often wade into water, wait for worm to naturally come out, and wind it around a stick. This is done slowly over several days
What does the term “arthropod” mean?
Jointed feet
Describe the appendages arthropods are so known for
Being segmented with multiple pairs of legs spread along body. Anterior limbs can be used for help with eating (as jaws or arms), middle appendages for movement, and posterior appendages for movement/reproduction.
Describe arthropod joints
There is an internal ball and socket arrangement which occurs in conjunction with strong muscles
Describe the basic features of the arthropods
Bilateral symmetry, eucoelomate (coelom greatly reduced), protostomes, triploblastic, have metameric segmentation (each body segment may carry pair of jointed appendages). At least one pair of limbs form the jaws
Describe the parts of the insect uniramous limb, from body to tip of limb
Body -> coxa -> trochanter -> femur -> tibia -> tarsus -> pretarsus
______ legs have a patella (kneecap)
Chelicerate
What are biramous limbs?
Limbs with two branches, one of which may function as a gill
The blood in arthropods is called _____
Hemolymph
Describe the body covering of arthropods
Cuticle, contains chitin. It forms a rigid exoskeleton that may have CaCO3. It is not uniform in thickness and is thin at joints to allow movement. The intersegmental areas are called “athrodial membranes”.
It is molted regularly followed by a period of rapid growth. It is also dead. SOOOO dead
How does respiration occur in arthropods?
In smaller ones it occurs across the body/limb surface. Larger ones respirate via trachial tubes lined with chitin. Openings leading to trachia are called spiracles
Describe excretion in arthropods
Performed by different types of organs, using antennary and maxillary glands in aquatic arthropods and coxal glands in terrestrial
The gut of arthropods is divided into 3 parts from mouth to anus: _____, _____, and _____
stomodeum, mid-gut/mesenteron, proctodeum
Briefly describe the nervous system of arthropods
Dorsal “brain”, paired ventral nerve cords which become bulbous ganglia in each segment.
What is tagmatization?
The process of grouping several metameric body segments into large “tagma”, such as is seen in insects
Describe the unique structure found in the midgut of arthropods?
The “peritrophic membrane” is a membrane protecting the epithelium of the gut from undigested food binding to it. It allows for gut compartmentalization that makes removal of undigestible wastes easier.
Describe the circulatory system of arthropods
Partially open. Blood enters the heart from the hemocoel through “ostia”, but exits the heart in vessels. Oxygenated blood moves through a series of sinuses.
Describe the sense organs of arthropods
Bristles and setae are outgrowths of the exoskeleton acting as touch receptors, for hearing, or as chemoreceptors. Can either have simple ocelli or compound eyes. Nocturnal insects also have highly developed olfactory senses
Describe the genitals and reproduction of arhtropods
Gonads are tubular with large paired ovaries (egg development from top to bottom).
Reproduction is almost always sexual with internal fertilization, though parthogenesis is common in Insecta and Branchiopoda, and some transfer sperm via spermatophores.
Describe the generalized insect mouthparts
Labrum - pushes food into mouth, forms the unpaired flexible roof
Mandibles - paired structures often adapted for chewing rough food
Maxillae - paired structures with sceleritized edges for biting. Bear “maxillary palps”, which are jointed appendages with a sensory function
Hypopharynx - Located between Maxillae and Labium, is the site where salivary glands empty
Labium - Develops from two fused appendages, bears the labial palps, which are sensory in function
How are a mosquitos mouth parts adapted for its lifestyle
Labium, mandibles, and maxillae are all elongated for piercing/sucking
Distinguish between a hemimetabolous life cycle and a holometabolous lifecycle. Name one organism that exhibits each
Hemi = One or several larval stages occur before adult metamorphizes. Larva > pupation > pupae > metamorphosis > adult. Ex. mosquitos Holo = Nymphs are the "child" life form, which are similar feeding habits to adults and simply grow into an adult. Ex. bedbugs
