Term
| This phylum is the largest in terms of the number of species. |
|
Definition
|
|
Term
| In terms of the number of individuals, the arthropods are... |
|
Definition
| Highly successful with a huge world population |
|
|
Term
| Name the two main evolutionary innovations of coelomate protostomes. |
|
Definition
1. Segmentation of the body cavity
2. Tagmatization |
|
|
Term
| The segmented body cavity of coelomate protostomes allows for... |
|
Definition
-specialization of the segments
-localized changes in the shape
-more precise control of movement |
|
|
Term
|
Definition
| The grouping or fusion of adjacent segments into larger functional units |
|
|
Term
| Which arthropods have tagmatization? |
|
Definition
*Subphylum Chelicerata
*Class Insecta |
|
|
Term
| Describe the tagmatization of the subphylum Chelicerata. |
|
Definition
~The prosoma (Cephalothorax) is the fusion of 6-7 anterior segments and has sensory and locomotion functions.
~The opisthosoma (Abdomen) is used for reproduction and is the fusion of 12 posterior segments. |
|
|
Term
| Describe the tagmatization of the Class Insecta. |
|
Definition
-Head=fusion of 4 anterior segments involved with sensory functions
-Thorax=fusion of 3 segments used for locomotion
-Abdomen=fusion of 11 posterior segments used for reproduction |
|
|
Term
| What are the 4 functions of the arthropod exoskeleton? |
|
Definition
1. Protection
2. Keeping water in for terrestrial organisms
3. Support
4. Locomotion |
|
|
Term
| What is the outermost layer of the arthropod exoskeleton? |
|
Definition
| The epicuticle. It is waxy and composed of firm lipoprotein with a lipid layer underneath it. |
|
|
Term
| The arthropod exoskeleton has a procuticle made of chitin and protein under the epicuticle. How does the procuticle differ in insects and crustaceans? |
|
Definition
*In insects, there is an exo and endocuticle. The exocuticle is a sclerotized layer while the endocuticle is not.
*In crustaceans, it has calcified and uncalcified layers. |
|
|
Term
| The procuticle is followed by epidermal cells and.... |
|
Definition
| Not uniform in thickness in arthropods |
|
|
Term
| Arthropods have joints which are really muscles that are... |
|
Definition
| Attached to the exoskeleton and exist as antagonistic pairs |
|
|
Term
| Molting is also called... |
|
Definition
|
|
Term
| Describe the general process of ecdysis. |
|
Definition
| The cuticle is split by water, air is taken up, and the blood pressure increases. A new cuticle is secreted before the old one is shed. |
|
|
Term
| The ecdysteriod hormone is produced in the prothoracic glands in the thorax of insects. How are they triggered to release? |
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Definition
| Stimuli is detected->hormone in brain activated->prothoracic glands activate->ecdysteriod hormone released |
|
|
Term
| In crusteeans, the release of ecdysteriod hormones is different from insects. What happens in them? |
|
Definition
| The X-organ in the eye stalks prohibit the Y-organ from producing the ecdysteriod hormone~the X-organ must be stopped from producing its hormone by albating the eye stalk to tell the brain to tell the Y-organ to produce the ecdysteriod hormone and make the crustacean molt |
|
|
Term
| Arthropod muscles are striated which... |
|
Definition
|
|
Term
| The strength of a muscle contraction in an arthropod is dependent on 4 things. Name them. |
|
Definition
1. The rate the nerve pulses are delivered to the fibers
2. The types of neurons innervating muscle fiber
3. Presence of neurons that inhibit action of other neurons
4. Five different nerve types can interact with a single muscle |
|
|
Term
| The blood vascular system of arthropods is made up of which components? |
|
Definition
| The heart, vessels, and the hemocoel |
|
|
Term
| The arthropod heart has perforations called ______ enclosed in the sinus or __________. |
|
Definition
|
|
Term
| The general arthropod circulatory system consists of.... |
|
Definition
| The heart sends blood into systolic system->body sinus->afferent(toward) vessel to gill->efferent(away from)vessel to heart->pericardial sinus->heart in diastolic system |
|
|
Term
| What are the 2 components of arthropod vision? |
|
Definition
| An ocellus and compound eyes |
|
|
Term
|
Definition
-is non-image forming
-possesses light absorbing pigment (vitamin A and protein)
*this light alters the molecule that generates action potentials across nerves |
|
|
Term
| What three components are needed for an eye to form an image? |
|
Definition
1. An ability to examine each component and monitor the light intensity across the image
2. A nervous system that can reconstruct an image
3. Light focused on a receptor surface |
|
|
Term
| How do arthropod eyes differ from human eyes? |
|
Definition
-Many lenses
-Image is right side up
-Focus of lenses cannot be varied
-Fewer receptor cells to sample image
-They can see into ultraviolet spectrum
(320-400 nm=UVA portion);(280-320 nm=UVB portion) |
|
|
Term
| An ommatidium is an individual unit of a compound eye and is made up of 4 parts. Name and describe them. |
|
Definition
1. Cornea-fixed focused lens with a large depth of field (objects 1 mm to several meters away in focus)
2.Crystalline cone-the gelatinous 2nd layer
3.Retinular cells-cylindrical with light-sensitive pigment
*Rhabdom-fine, microvilli processing the light-sensitive pigment
4.Neural Cartridge (Axon bundle)-ganglia that receive information from the retinular cells and send it for processing |
|
|
Term
| A superposition eye is one type of arthropod eye. Describe it. |
|
Definition
-Shielding pigments are retracted
-50% of light is hitting the rhabdom from other ommatidia
-Effective in low light
-Ex. crayfish, lobsters |
|
|
Term
-The ommatidia are separated by shielding pigments
-only 0.1-1% of light hitting the rhabdom is from other ommatidia
-best in bright light
-exs=honey bees, locusts |
|
Definition
| These are characteristics of the apposition eyes of arthropods. |
|
|
Term
| The important basic facts about arthropod reproduction.... |
|
Definition
*sexual!!
*most species are gonochoristic
*terrestrials forms have internal fertilization
*Parthenogenesis is seen in some Insects and Branchiopods (brine shrimp, clam shrimp, water fleas) |
|
|
Term
| The subphylum trilobita (class trilobita) was abundant 500 million years ago but went extinct 275 million years ago. Why do we study them? |
|
Definition
-bottom dwellers in oceans
-scavengers
-subsequent evolution resulted in specialized appendages
-Appendages were biramous (the ends fork into two parts) |
|
|
Term
| The subphylum Chelicerata is made up of these 3 classes. |
|
Definition
1. Class Merostomata
2. Class Arachnida
3. Class Pycnogonida |
|
|
Term
| There are only 4 living species in the Class Merostomata including the....all are found...How do they reproduce and what unique "gills" do they have? |
|
Definition
-Horseshoe crab; in eastern North America, SE Asia, and Indonesia
-External reproduction where the male fertilizes eggs as they are deposited onto the sand
-They have book gills |
|
|
Term
| What is significant about the blood of the Merostomata? |
|
Definition
-Oxygen is transported by hemocyanin
-It contains amebocytes that function similar to white blood cells
-It can be used to detect gram-negative endotoxins in pharmaceuticals
*amebocytes react with endotoxins |
|
|
Term
| What are the general characteristics of the Class Arachnida? |
|
Definition
-about 1/2 of all chelicerata are spiders
-prosoma=head and thorax
-opisthosoma=abdomen
-almost all terrestrial
-tear apart food and inject venom
-pedipalps are modified for grabbing, killing, or reproducing
-have 4 pairs of walking legs |
|
|
Term
| Class Arachnida is composed of which organisms? |
|
Definition
| Spiders, ticks, mites and scorpions |
|
|
Term
| The book lungs and tracheae of arachnids are involved with gas exchange. Describe how. |
|
Definition
Book lungs allow gas exchange to occur as blood flows through folded sheets of tissue. Book lungs have slit like openings to the outside called spiracles.
-The trachaea are made up of branching tubules that terminate in tissues, which allows blood to bypass the circulatory system
*One or both may be present in one organism |
|
|
Term
| Which order of spiders has spinnerets? |
|
Definition
|
|
Term
| What details are important about spinnerets? |
|
Definition
-up to 4 pairs of per individual
-they are connected to abdominal glands secreting silk proteins
-up to 7 types of glands in one individual |
|
|
Term
| What are the 7 functions of spider silk? |
|
Definition
1. Providing a home
2. Catching and immobilizing prey
3. Mating (males deposit sperm on webs)
4. Collecting water
5. Protecting eggs
6. Safety lines while climbing
7. Parachuting (dispersal mechanism) |
|
|
Term
| Contrast the black widow to the brown recluse. |
|
Definition
-The black widow's venom is a neurotoxin that is fatal in 4 out of 1000 cases.
-The brown recluse's venom is hemolytic (it causes death of tissues and skin around the bite). It is mild to serious and occasionally fatal |
|
|
Term
| Daddy Longlegs are not spiders. In fact,... |
|
Definition
*They belong to the order Opiliones [Harvestman]
*The prosoma and opisthosoma is fused
*No venom or silk glands
*Not venomous or poisonous
*Feeding apparatus allows consumption of food chucnks |
|
|
Term
| Sea spiders belong to which class? |
|
Definition
|
|
Term
| What are the body systems of sea spiders like? |
|
Definition
-Sucking mouth parts (elongated proboscis)
-Complete digestive system
-Lack specialized respiratory and excretory systems |
|
|
Term
| The sea spider body is unique because... |
|
Definition
*Most of the body is the prosoma
*The opisthosoma (abdomen) is reduced to a short stump |
|
|
Term
| Organisms belonging to Class Pycnogonida (the sea spiders) are all marine and found in oceans. They have an oviger. What is that? |
|
Definition
| A set of organs used to groom legs and the trunk in both sexes. Males also use it to brood eggs. |
|
|
Term
| The subphylum Mandibulata is mainly defined by... |
|
Definition
| Appendages (mandibles) on the third head segment that are modified for feeding |
|
|
Term
| What are the three classes belonging to the subphylum Mandibulata? |
|
Definition
1. Class Myriapoda
2. Class Insecta
3. Class Crustacea |
|
|
Term
The Class Myriapoda means ____ _____ and is made up of 2 orders, which are....
*If eyes are present, they are actually.... |
|
Definition
"Many feet"
1. Order Chilopoda (Centipedes)
2. Order Diplopoda (Millipedes)
*Ocelli |
|
|
Term
| The Chilopoda (Centipedes) are predators like.... |
|
Definition
| Earthworms and insects; they have maxillipeds with poison fangs and one pair of appendages per body segment |
|
|
Term
| Diplopoda (Millipedes) are what kind of feeders? |
|
Definition
|
|
Term
| How many appendages do the diplopods have per body segment? Why? |
|
Definition
| Two!! The difference in the number of appendages between millipedes and centipedes reflects a difference in diet. |
|
|
Term
| To belong to the class Insecta, organisms must.... |
|
Definition
| Have 2 pair of wings and not be found in the deep sea |
|
|
Term
| About 20% of the Insecta are parasitoids. What does this mean? |
|
Definition
| They develop in the embryos or larva produced by other insect species and devour the host tissue from the inside out |
|
|
Term
| What two orders of insects are the most common parasitoids? |
|
Definition
| Order Diptera (true flies) and Order Hymenoptera (wasps) |
|
|
Term
| Name and describe the two main components of the insect sensory system. |
|
Definition
-Visual: One pair of compound eyes and 3 ocelli
-Auditory: Tympanal Organs~ consist of an external membrane (the tympanum) backed by an air sac and sensory neurons; occur on just about any part of the organism |
|
|
Term
| How do insects achieve water conservation (in relation to spiracles)? |
|
Definition
| *They have 1-2 pairs of spiracles on the thorax and a pair on each abdominal segment; these can be closed to prevent water loss |
|
|
Term
| How do insects achieve water conservation (in relation to the Malpighian tubules)? |
|
Definition
Malpighian tubules are excretory organs. There are up to 250 pairs in the hemocoel.
*Waste from the protein metabolism travels to the Malpighian tubules (acidity of tube contents cause precipitation) then uric acid is dumped into the digestive tract. Water is reabsorbed in the rectum before waste is released. |
|
|
Term
| How do insects achieve gas exchange? |
|
Definition
| They use Tracheal system-internalized gas exchange. This means their body is lined with chitin and this chitin is shed with each molt. The tracheoles branch further and terminate in the tissues. This allows them to bypass the blood circulatory system. |
|
|
Term
| What are the six features that favor the evolution of flight in insects that evolved 300-400 million years ago? |
|
Definition
1.Striated muscles
2.Antagonistic muscles in a jointed skeleton
3.Small body size
4.Efficient gas exchange system
5.Highly developed nervous and sensory system
6.Water impermeable covering |
|
|
Term
| To fly, two things are mandatory. Name them. |
|
Definition
|
|
Term
| When lift force exceeds the weight of an object, what happens? |
|
Definition
|
|
Term
|
Definition
| If pressure is greater on the bottom of a wing in motion when the air flow rate is faster on the top of the wing |
|
|
Term
| Define steady-state flight. |
|
Definition
| Lift is generated from steady flow over the upper wing and body (example= aircraft) |
|
|
Term
| What type of flight do insects use? |
|
Definition
| They use both steady-state and non-steady-state flight. |
|
|
Term
| What is non-steady-state flight? |
|
Definition
| Additional life is generated by wing flapping (propulsive force) that creates small whirlpools of air called vortices |
|
|
Term
| An instar is a distinct developmental stage of which arthropod class? |
|
Definition
|
|
Term
| Butterflies, ants, flies, and wasps undergo what type of development? |
|
Definition
Holometabolous (complete metamorphosis);
Egg->Larva(several instars)->Pupa->Adult |
|
|
Term
| Hemimetabolous development (incomplete metamorphosis) is seen in... |
|
Definition
Grasshoppers, cicadas, and roaches; Eggs->Nymph(several instars)->Adult
*It is the development of wings and reproductive organs |
|
|
Term
| Animals such as springtails and silverfish undergo direct development. This is known as... |
|
Definition
| Ametabolous development; Eggs->Juvenile->Adult; Young are similar to adult except in size and sexual maturity |
|
|
Term
| Broadly speaking, ALL crustaceans have.... |
|
Definition
*A head with 5 pairs of appendages, including 2 pairs of antennae
*Nauplius larva: triangular with 3 pairs of appendages and a single medial eye |
|
|
Term
| The subclass Malacostraca is made up of 60% of all crustaceans and are commonly called... |
|
Definition
| Shrimp, crabs, and lobsters |
|
|
Term
| The head and thorax of the Malacostraca is fused as a single unit (the cephalothorax) and covered by... |
|
Definition
|
|
Term
| The head region of the Malacostraca... |
|
Definition
-1st and 2nd pair of antennae are sensory structures
-mandibles crush food
-maxillae generate water currents and manipulate food |
|
|
Term
-maxillipeds manipulate food
-perepods (walking legs)~ the first 1-3 are sometimes chelate (claw bearing and biramous) and used for feeding or defense |
|
Definition
| This describes the thorax region of the Malacostraca. |
|
|
Term
| The abdomen region of the Malacostraca has.... |
|
Definition
-Pleopods that are used for swimming, generating respiratory currents, and brooding eggs
-Uropods that are used for swimming |
|
|
Term
| Common names for organisms belonging to the Subclass Branchiopoda are... |
|
Definition
| Sea monkeys, clam shrimp, water fleas |
|
|
Term
| Organisms belonging to the Subclass Branchiopoda... |
|
Definition
-filter feeders
-have a bivalved carapace (some lack a carapce)
-Some live in extreme salinity or temporary ponds
-Compound eyes may or may not be stalked |
|
|
Term
| Stomatopods like the mantis shrimp belong to the order.... |
|
Definition
|
|
Term
| Name the 4 ways in which the Order Stomatopoda is unique. |
|
Definition
1. 8 pairs of thoracic legs (2nd pair is modified for smashing or spearing)
2. Striking speeds up to 1000 cm/sec
3. Jointed head- anterior to posterior move independently
4. Well-developed eyes with complex color recpetors |
|
|
Term
*These are common in both marine and freshwater, but live mostly on the bottom
*Head and body in a bivalved carapace
*body is mostly made up of the head
*The rest of the body only has 2 pair of appendages |
|
Definition
| Subclass Ostracoda (the Ostracods) |
|
|
Term
| Important general information about copepods: |
|
Definition
-Mostly marine and feed of phytoplankton
-A major component of zooplankton
-usually less than 1-2 mm long
-Have a high SA to V ratio to uptake oxygen through the body surface without gills |
|
|
Term
| On the body of a typical copepod, |
|
Definition
*3 ocelli~2 point forward and up and 1 points down
*1st antenna=sensory function
*2nd antenna=used for locomotion
*2nd maxilla-used to collect phytoplankton
-6 thoracic segments(1st and sometimes 2nd are fused with head)
-5 abdominal segments~ no appendages here!! |
|
|
Term
| Parasitic copepods are differet from regular copepods because.... |
|
Definition
| Parasitic ones have more emphasis on highly modified reproductive structures |
|
|
Term
| The subclass Pentastomida (Pentastomas) are all.... |
|
Definition
| Internal parasites of vertebrates usually found in the lungs and nasal passages of reptiles, but can be found in a few species of amphibians, birds and mammals |
|
|
Term
| All species of Pentastomas are gonochoristic and consume the host's blood. How do they get out of the host? |
|
Definition
| Encysted forms exit in nasal secretions or saliva |
|
|
Term
| What are the 5 intermediate hosts of Pentastomas? |
|
Definition
-Raccoons
-Cockroaches
-Muskrats
-Armadillos
-Bats |
|
|
Term
| The subclass Cirripedia is commonly called... |
|
Definition
|
|
Term
| Regardless of all other characteristics, barnacles are crustaceans because... |
|
Definition
| They have nauplius larvae!!! |
|
|
Term
| The subclass Cirripedia (Barnacles) have a highly modified crustacean body plan including... |
|
Definition
-a reduced head and 1st antennae (2nd antennae is lost)
-thick calcium carbonate shell secreted by "mantle" tissue
-no abdomen, no gills, no heart |
|
|
Term
| Due to a sessile life style, the subclass Cirripedia (Barnacles) feed by being... |
|
Definition
*Active suspension feeders: When water flow is less than 1 cm/sec, they wave cirri in the water
~Passive suspension feeders-If water is flowing greater than 3 cm/sec, they leave the cirri outstretched in the opposite direction |
|
|
Term
| What is so great about barnacle cement? |
|
Definition
-a thin layer can support up to 7,000 pounds
-it won't melt at 3,300 degrees C (6,000 degrees F)
-it is not soluble in most acids, alkalines, organic solvents or water
-it keeps invertebrates OFF boats!! |
|
|
Term
| Bernoulli's Theorem states... |
|
Definition
| At the bottom of a sponge, there is high pressure but low flow of water. At the top of that sponge, there is lower pressure, but a higher flow of water. Pressure decreases (and flow increases) as you go from bottom to top. This applies to air pressure and flying too! |
|
|
Term
| What environments are echinoderms found in? |
|
Definition
|
|
Term
| What is unique about the symmetry of echinoderm larvae relative to the adults? |
|
Definition
*Larvae are bilaterally symmetrical.
*Adults show a typical 5-pointed (pentamerous) radial symmetry and therefore have no anterior or posterior ends. They have oral (the mouth bearing) and aboral surfaces. |
|
|
Term
| What is the composition of the internal skeleton in echinoderms? |
|
Definition
-Up to 95% calcium carbonate
-Up to 15% magnesium carbonate
-Small amounts of salts and trace metals
-A tiny bit of organic material |
|
|
Term
| How does production of the echinoderm skeleton differ from that occurring in molluscs? |
|
Definition
~In molluscs, the skeleton comes from minerals being deposited into an extracellular protein matrix.
*In echinoderms, each component of the skeleton is made individually in specialized cells derived from embryonic mesoderm. |
|
|
Term
| What is the duo-gland adhesion system seen in echinoderms? |
|
Definition
-One or more gland cells on each tube foot secrete an adhesive that temporarily binds the tube foot to a substrate.
-Nearby gland cells omit a different chemical that will break the bonds, releasing the tube foot. |
|
|
Term
| List the 4 classes of Echinodermata and give examples. |
|
Definition
1. Class Crinoidea- sea lilies, feather stars
2. Class Stelleroidea- brittle stars, sea stars
3. Class Echinoidea- sand dollars, sea urchins, heart urchins
4. Class Holothuroidea- sea cucumbers |
|
|
Term
| What is the defining characteristic of the echinoderm class Crinodea? |
|
Definition
| The main part of the body is supported above the substrate either by a long stalk or by a series of grasping claws (cirri). |
|
|
Term
| How do crinoids (a class of echinoderms) feed? |
|
Definition
| They collect food by extending their arms, pinnules, and tube feet into surrounding water currents. The arms and pinnules start moving by contractions of extensor muscles and ligaments. As food particles come into contact with the tube feet, they get trapped in mucous and flicked into the ambulacral grooves. The food is then transported to the mouth by cilia. They do not use tube feet for locomotion! |
|
|
Term
| Which parts of the generalized water vascular system are missing in crinoids? |
|
Definition
| Criniods do not have ampullae or a madreporite in their water vascular system. |
|
|
Term
| What are the 2 defining characteristics of Class Stelleroidea, Subclass Ophiuroidea? |
|
Definition
1. Well-developed ossicles in the arms form a linear series of articulating "vertebrae" joined together by connective tissue and muscles
2. The oral surface has 5 pair of invaginations (bursal slits) used for gas exchange and used as brooding chambers for developing embryos |
|
|
Term
| How do organisms belonging to the Class Stelleroidea, Subclass Ophiuroidea feed and how does their digestive system differ from most other echinoderms? |
|
Definition
*Many are deposit feeders that ingest sediment and consume the organic portion. They also capture small animals in sediment and eat those alone. *Some are suspension feeders and filter food particles from the water. Moveable connective tissue lets them stiffen their arms and hold the filtering posture for long time periods. *Some are carnivores or scavengers.
-Their digestive tract is different because it only has a single opening. They have a mouth, but no anus. |
|
|
Term
| Organisms belonging to the Class Stelleroidea, Subclass Ophiuroidea lack what part of the generalized water vascular system? |
|
Definition
| *Ampullae, BUT one organism can have several madreporites in their water vascular system |
|
|
Term
| In the echinoderm Class Stelleroidea, Subclass Asteroidea... |
|
Definition
| The gonads and portions of the digestive tract uniquely extend into each arm |
|
|
Term
Track the flow of food from the mouth to the anus of a sea star.
*Class Stelleroidea, Subclass Asteroidea |
|
Definition
*Food enters the downward facing mouth and passes into the short esophagus
*It then passes upward into the lower stomach (the cardiac stomach). This lower stomach is confined to the central body disc and is responsible for digestion of food.
*Above this is the upper or pyloric stomach. Its branches radiate out into each arm as pyloric caeca. Their goal is to secrete digestive enzymes and absorb digested nutrients. They are also primary storage sites for broken down food.
*The anus lines the aboral surface, nearly in line with the mouth. |
|
|
Term
| What are the papulae and what is their function? |
|
Definition
| Thin non-calcified outfoldings of the outer body wall; Serve a respiratory function |
|
|
Term
| These are made up of 2 (sometimes 3) calcium carbonate ossicles [valves]. The ends can be moved together or apart by muscles. The 2 jaws are supported by a nonmoveable, basal ossicle. They function in removing unwanted organisms and debris that contact the surface of the animal. They can even capture live prey in some species. |
|
Definition
| This describes pedicellariae and their function. |
|
|
Term
| In the echinoderm class Echinodea, what is the function of the spines? |
|
Definition
| They are used for protection. In some species, they are actively involved in locomotion. They can brace the animal when it creeps into crevices, help in gathering food, and in defense. Toxins may be sent out through them or through glands associated with them. |
|
|
Term
| Only seen in the class Echinodea, what is Aristotle’s lantern? |
|
Definition
| It is the name for the complex system of ossicles and muscles surrounding the esophagus. The teeth in this system can be protruded from the mouth and moved in various directions to eat seaweed or to scrape food (like algae) from solid substrates. |
|
|
Term
| In the class Holothuroidea, how have the tube feet been modified over evolutionary time? |
|
Definition
*The oral tube feet have become large, feathery tentacles that can be protracted from the mouth and used to capture food. Each tentacle can be operated by a single, large ampulla.
*The tube feet of surface-living cucumbers are used in locomotion and attachment. |
|
|
Term
| What is the respiratory tree and why is it unique to the class Holothuroidea? |
|
Definition
-They are the only echinoderms to have internal respiratory structures called respiratory trees.
-The trees are found (one on each side of the body) terminating in the cloaca.
-The animal pumps water into the respiratory trees by contracting the cloaca and oxygen diffuses through from the walls of the trees into the fluid of the body cavity |
|
|
Term
| In the class Holothuroidea, what is the process of evisceration and why might it happen? |
|
Definition
Generally, it is the expelling of the entire digestive system along with the respiratory trees and the gonads. It would happen if the animal is irritated to incapacitate an intruder.
*Literally, the animal liquidizes and ruptures the connective tissue attaching the viscera to the inner body wall. All lost parts are eventually reformed. |
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Term
Describe the construction of the water vascular system (WVS) and how it functions. [PART 1]
*Ambulacral grooves
*Madreporite
*Stone canal
*Water vascular system ring canal |
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Definition
-It is made up of several canals that form during embryonic development.
-Canals lead to thin-walled tube feet, which are extensions of the WVS that penetrate the body wall and skeleton in regions called the ambulacral grooves.
-The internal canals are linked to the outside water through a sieve plate called a madreporite.
-The madreporite leads to a stone canal (reinforced with spicules or CaCO3), then to a WVS ring canal which forms a ring around the esophagus in most species. |
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Term
Describe the construction of the water vascular system (WVS) and how it functions. [PART 2]
*Polian vesicles
*Tiedemann's bodies
*Radial canals
*Ampullae
*Tube feet |
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Definition
-Accessory fluid-storage structures called Polian vesicles and Tiedemann's bodies are usually associated with ring canals.
-Tiedemann's bodies also filter fluid from the WVS into the main body cavity.
-5 (or a multiple of 5)radial canals radiate symmetrically from the WVS ring canal.
-Pairs of bulb-shaped ampullae connect to the radial canals. Each ampulla serves one tube foot.
-Tube feet don't always have circular muscles, so they can't extend. Fluid is pumped into the tube foot by the ampulla, extending the foot. |
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Term
| What is the significance of the one-way valve between the ampulla and the radial canal in the water vascular system of echinoderms? |
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Definition
-It makes sure the fluid flows from the ampulla to the tube foot when the ampulla contracts.
-When the tube foot retracts, its longitudinal muscles retract and the valve directs fluid back to the ampulla, stretching the ampullar muscles for the next cycle. |
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