Zoology Test 3 Review

How many species of mollusks are there? Where do mollusks rank in terms of diversity compared to other Phyla?

   There are about 50,000 species in total, mollusks rank as the second most diverse type of phyla.

  Describe the function of the muscular foot, mantle, visceral mass, and shell regarding the general body plan of a mollusks.

The muscular foot, which is a bundle of muscles that are mainly used for anchoring and locomotion.

The mantle houses the gills and can secrete the shell in some mollusk species.

The visceral mass is where all of the internal organs are found.

  The shell is a hard external structure that mainly functions as protection. It is also primarily made from calcium carbonate.

What is a radula? What are the benefits or downsides of a radula? How does this structure relate to the lifestyle the organism?

    It is a rasp-like structure that is designed for the scraping of food off of surfaces.

The downside of a radula is that the organism’s teeth could wear quickly.

A benefit of a radula, however is that the teeth are replaced daily and rather quickly.

The structure and design of a radula varies by species (example: in cone snails, it is designed for the injection of venom).

  What is the relationship between a trochophore and a veliger?

  A trochophore, which is a swimming larvae, will eventually develop into a veliger, which is a more mobile larvae.

What does Monoplacophora roughly translate to?

“Bearing One Plate”

  What is an interesting fact about Monoplacophorans relating to their “recent” discovery as extant species?

Their serial arrangement of their gills and other various organs has shown possible evolutionary relations to the Annelids.

Why are Monoplacophorans described to be “limpet-like”, but are not considered to be true limpets?

  Since they have a small appearance and a cap-like shell, this makes them look similar to limpets. They are not considered “true limpets” because of their organs being serially repeated.

What does Scaphopoda roughly translate to? What are the common name(s) for scaphopods?

“Boat-foot,” the common names are tusk shells and tooth shells.

What sense organs do Scaphopods have?

Since they do not have eyes, they possess sticky tentacles that are used for preying on organisms living in substrate.

What are captacula?

They are sticky tentacles that contain cilia.

  Relate the anatomy of a Scaphopod to their ecology (i.e., how does their unique morphology relate to their lifestyle)

The morphology of a scaphopod relates to their ecology because by having a shell that is open on both sides, it allows potential food items to come in from the top, while their mouth is anchored to the sand or substrate.

   What does Aplacophora roughly translate to?

“Bearing no plates”

What is unique about the Aplacophorans? How do they defend themselves? Were they always thought to be mollusks?

They lack a shell, they defend themselves by utilizing their calcium spicules. They were not always thought to be mollusks.

  What does Polyplacophora roughly translate to? What is the common name(s) for this taxon?

“Bearing many plates,” the common name is Chitons.

What does Gastropoda roughly translate to? What is the common name(s) for this taxon? How diverse is this taxon? Where do they live?

Gastro: Stomach. Podos: Foot. The common names are snails, limpets, sea hares, and slugs. This is the second most diverse class, and they live in marine, freshwater, and terrestrial areas.

  What is durophagy? How has durophagy related to the evolution of gastropod shells?

The predation of exoskeleton or hard-shelled animals, it relates to the evolution of gastropods because they have developed sturdier and stronger shells over time.

What is an operculum?

A corneous “door” leading into a gastropod’s shell.

  What is unique about gastropod reproduction? Describe the courtship behaviors associated with gastropods.

  Love darts are used during reproduction, eggs are laid underwater or in a moist soil, and there is no larval stage and they hatch as miniature adults.

The courtship behaviors between gastropods is a type of mating dance, which can last up to six hours. During this, there is constant lip and tentacle biting.

What is unique about gastropods in the genus Conus? Describe how the unique aspects of their anatomy in relations to their ability to cause severe pain by injecting venom.

They are seen as unique because of their ability to envenomate using their harpoon-filled proboscis. This proboscis is filled with toxic venom, which permits the ability to cause severe pain.

What does Bivalvia roughly translate to? What is the common name(s) for this taxon?

  “Two-shells,” The common names are mussels, clams, scallops, and oysters.

  Describe the biology of a typical bivalve and how it differs from other mollusks.

A typical bivalve has a two-piece hinged shell. They are different from other mollusks since they lack a radula for feeding, and are filter feeders instead.

  What does infaunal and epifaunal mean?

  Infaunal means to burrow in the substrate.

Epifaunal means to attach to the substrate.

  What is unique about freshwater mussels in the family Unionidea? Where do they live? Why are they important?

They can create “fish-like” lures to spread their larvae. They live in the Eastern U.S. Rivers. They are important because they are endangered, with 16 extinct species, and 70 that are threatened.

  Describe the life cycle of a typical freshwater mussel. Emphasize lures, glochidia, and the hosts of the glochidia.

·         Male mussels release their sperm into the water for females to catch. Fertilization of eggs occurs.

·         The eggs develop into glochidia, or fish parasites.

·         The lure develops, which is designed to attract a fish host. The mussel will eject glochidia onto the fish host after it interacts with the lure.

·         The glochidia encysts onto the fish host’s gills. These get moved and transported around, and eventually form juveniles, known as spat.

·         The spat will then release into the benthos and grow into adults.

  What are pearls? What bivalves can produce pearls? How are they produced?

The natural defense against any parasites that can potentially damage or harm bivalve shells. Oysters, mussels, and clams can all produce pearls. They are produced through a substance called nacre, a by-product of parasite elimination.

What habitats are mollusks found in? What proportion of mollusks are found in these environments?

they are found in marine, terrestrial, and freshwater habitats

50% are marine and 25% of marine life are mollusks, 30% are freshwater, and 17.5% are terrestrial

  Describe how the true body cavity relates to the evolutionary success of Mollusks.

it allows for greater morphological diversity, more diversity of internal organs and organ systems, and allows for the existence of a true digestive, circulatory, and nervous system

Some mollusks are filter feeders; describe the ecology of a filter feeding mollusk. What are the benefits and downsides of being a filter feeding organism?

mollusks like clams and mussels utilize structures like their gills to filter out tiny particles and plankton from the water

the benefits of being a filter feeder are efficient nutrient acquisition, which can provide support in the mollusk’s growth and reproduction, as well as the ability to thrive in aquatic environments

the downsides of filter feeding are competitions for food sources, threats from predators, and changes from the environment

Describe the respiratory system of a mollusk. Do they have gills? Do they have lungs? How does respiration differ between aquatic and terrestrial mollusks?

Mollusks typically rely on their gills, also called ctenida for respiration purposes, they do not have lungs

Aquatic mollusks rely solely on their gills for respiration and breathing

Do mollusks use extracellular or intracellular digestion? Are there exceptions to this digestion methods?

they typically utilize an intracellular digestion system

the exception of this is Class Bivalvia, who are filter feeders and can only feed on tiny particles of a certain size

What are the nephridia (singular is nephridium) in mollusks?

It is an excretory part of the mollusk circulatory system that is used to filter blood and coelomic fluid

  Describe the nervous system of the mollusk. What taxa have more advanced nervous systems?

It has a well-developed head, anterior cerebral ganglia, and sense organs

cephalopods have grown to form a large brain, and they exhibit more complex behaviors, especially order Cephalopoda

    What sensory organs do mollusks possess? Where are the sense organs often located?

they typically possess organs like statocysts, sensory tentacles, and eyes

these sense organs are often located in the head, mantle cavity, and mouth area

Are mollusks hermaphroditic? Dioecious? Or both?

They can be both hermaphroditic and dioecious

  What is a trochophore?

a swimming larva stage for mollusks

   What is a veliger?

what a trochophore becomes, a more mobile mollusks larvae stage

Where do polyplacophorans live? What feeding structure do they use?

they primarily inhabit rocky, intertidal zones

they utilize a radula to scrape algae

What is nacre?

also known as mother-of-pearl, is a material produced by some mollusks as an inner shell layer, it is also the material that pearls are made of

  What are zebra mussels (Dreissena polymorpha) and why are they known as one of the worst aquatic invaders in the United States.

they are an invasive species of mussel from Europe, they are one of the worst invaders in the U.S. because they have already rapidly spread in 20 years, and they overgrow on the native freshwater mussels, suffocating them

  Describe the life cycle of an oyster.

sperm and egg are released and become fertilized

the fertilized eggs develop into trocophore larvae

trocophore larave develop into shelled veliger larvae

veliger larvae develop into spat and settle down onto shallow substrates

lastly, they develop into full-grown adults

  What is torsion in gastropods? What is the result of torsion? Do larval gastropods have torsion?

a process that moves the anal opening and mantle cavity to the front of the body shortly after hatching

the result of this process is the mantle cavity and anus being positioned in the anterior body, over the head and mouth, and the gut and nervous system are twisted

it takes place during the veliger larval stage, usually very rapidly

  Describe the sensory structures associated with the head of a gastropod.

the eyes of a gastropod have photoreception-like traits, while the lower mechano/chemosensory tentacles sit below the eyes

Describe the pros and cons of being a gastropod with a shell

pros:

protection from predators and environmental hazards

provides a stable structure to assist gastropods in navigating and surviving in various habitats

shells can house a radula, which can allow gastropods to consume food efficiently

cons:

a shell can add weight, which can negatively affect speed and mobility

  Describe the pros and cons of being a gastropod without a shell

pros:

gastropods with no shell can move with more speed

they have the ability to adapt to more environments without the constraints of a shell

some shell-lacking gastropods have specialized feeding organs that permit them to consume food effectively

cons:

no shell means the gastropod is more vulnerable to its predators

they may face potential environmental challenges where a shell can come in handy

  What is unique about Banana slugs in the genus Ariolimax? 

they can reach up to 10 inches in length, they rely on moisture to survive, and they are detritivores, meaning they feed on decomposing matter

  What are parapodia? What gastropods are known for their parapodia?

they are wing-like flaps that are used for motion

Order Pteropoda, or pelagic sea snails, are known for their parapodia

  Describe the anatomy of true limpets in the family Patellidae.

the shell is typically a low, flat oval that is bilaterally symmetrical, and it covers the entire body

they also possess a strong, muscular foot that assists in movement and feeding

the shell’s shape is conical or dish-shaped, and that is a key characteristic of this organism

What are the ecological benefits of bivalves? Why do biologists care about protection these organisms?

some ecological benefits of bivalves are water filtration and contributing to biodiversity through habitat provision

bivalve protection is important because they are essential organisms that help in maintaining a healthy aquatic ecosystem, and their decline can negatively impact biodiversity and water quality

Describe the bivalve development process. What larval stages do they exhibit? Do they undergo internal or external fertilization?

it is usually internal fertilization, they exhibit two larval stages, which are trochophore (stationary larva stage) and a veliger (a free-swimming larval stage)

  What does Cephalopoda roughly translate to? What is the common name(s) for this taxon?

It roughly translates to “head foot,” and the common names are cephalopods, cuttlefish, octopi, squids, and nautiluses.

  What is a cephalopod beak? What are the benefits or downsides of a beak? How does this structure relate to the lifestyle the organism?

  It is a specialized structure that can be located in cephalopods, specifically squid and octopuses. It functions similarly to how jaws would.

A benefit of the beak is its versatility, which allows the cephalopod the ability to adapt to catch various prey types and sizes.

  A downside of the beak is that it could possibly limit different feeding strategies of a cephalopod.

The beak relates to the lifestyle of the cephalopods since it is adapted to their lifestyle as predators, allowing them to successfully and quickly catch their prey.

  Describe the circulatory system of cephalopods and describe the benefits of this physiology.

A cephalopod typically has a closed circulatory system. This means it has two brachial hearts that pump blood to its gills/ctenidia, and a systematic heart that pumps blood and other nutrients from the gills/ctenidia to the rest of the body. The benefits of this physiology is that it permits the organism to be adapted for a more active lifestyle.

How do cephalopods hunt their prey?

  They can hunt their prey in various ways. Some of these hunting tactics include ambushing, luring with the use of mimicry and bright/unusual coloring, and stalking to catch a prey organism by surprise.

Describe the advanced eyes of cephalopods. Why do some biologists argue that cephalopod eyes are more advanced than human eyes?

  These organisms’ advanced eyes have convergently evolved just like human and other vertebrates’ eyes. Some individuals argue that they are more advanced than human eyes since cephalopod eyes do not appear to have any blind spots.

Describe the intelligence of cephalopods. Why and how are they so intelligent? What are the ecological benefits of this character?

Since they have a brain that is larger than any other invertebrate, cephalopods have shown a wide range of various cognitive abilities. These include solving different puzzles, great memories, and the ability to learn different things.

It is estimated that they are super intelligent because this incredible intelligence evolved as a response to different kinds of ecological pressures they face, like finding and locating food in hazardous situations.

Some ecological benefits that are gained from this are predator avoidance tactics, enhanced social interactions, and great foraging efficiency.

  What are the 3 subclasses within class Cephalopoda? What are the 4 orders within subclass Coleioidea?

The three subclasses are: Nautiloidea, Ammonoidea, and Coleoidea.

The four orders are: Sepiida, Myopsida, Octopoda, and Vampyromorphida.

What cephalopod taxa are extinct? What is unique about the biology and anatomy of these two extinct cephalopods?

  The extinct groups are Superorder Belemnoidea and Subclass Ammonoidea. The two factors that make these two taxa unique are their hunting adaptations and their rather unique shell structures (ex: the belemnites’ guards and the ammonites’ more ornate shells when compared to modern day nautiloids).

Describe the general biology and anatomy of Nautiloids. How diverse are they?

The biology consists of three main sections: the Septa, Chamber, and Siphuncles. The septa serves as the divider between the chamber and siphuncles. The chamber is a hollow, gas filled section. The siphuncles are a vein-like pump that serves the purpose of maintaining buoyancy by pumping salty blood and dehydrating the chambers. They used to be diverse, but now there are only 6 known living species remain.

  How are cephalopods capable of changing coloration? What is the underlying anatomy and physiology of this behavior? What colors are produced by Chromatophores, Iridophores, and Leucophores. Are these colors produced through physiology (i.e., muscle) or structure (i.e, reflection).

Color changing occurs through the use of chromatophore, which are pigment sacs that change color based on the muscles that expose pigments that are below them. The underlying anatomy for this process is the iridophores and leucophores, which are light reflecting cells that alter the chromosomes’ colors.

What colors are produced by Chromatophores, Iridophores, and Leucophores. Are these colors produced through physiology (i.e., muscle) or structure (i.e, reflection).

         The colors produced by chromatophores are yellows, reds, and browns, and they are produced through muscle.

The colors produced by iridophores are blues and blacks, and they are produced through reflection.

The colors produced by the leucophores are whites, and they are produced through reflections.

Describe the alternative reproduction strategy of cuttlefish that involves “sneaker males” and sexual mimicry.

This mating tactic involves the presence of “sneaker males,” which are males that are smaller in size and compete with the normal sized males for reproduction purposes. They use sexual mimicry to alternate between both female and male looks. This prevents them from being spotted by the larger males. This procedure leads to the sneaker males being successful in mating with the females behind the larger males’ backs.

     Describe the general anatomy and swimming motion of Myopsids. How does their external anatomy relate to their ability to move around? What habitats are they most likely to be found in?

  The general anatomy of Myopsids contains features and parts that aid in their swimming abilities, like lens eyes for greater vision, and their arms, tentacles, and siphons.

The swimming motion of the Myopsids can be described as unique, and this is thanks to their 8 sucker-covered arms and 2 retractile tentacles. This allows the Myopsids to swim efficiently through the water with their arms and tentacles behind them.

They are typically found in the pelagic zone of the waters, which is about 3,000 feet deep into the sea.

  What is the gladius/pen?

This is the internal shell of the squid that provides structural support.

  What is the function of ink sacs?

  This is a squid’s main source of defense. If threatened, it will release the ink into the face of its predator to make a quick getaway.

  What is significant about the giant squid, Architeuthus dux?

It is classified as the longest invertebrate on earth, measuring about 20 meters long.

      What are muscular papillae and what is their function?

These are small, cone-like muscles that are found in the heart’s ventricles. They allow an octopus to change their texture.

  What is unique about the octopuses in relationship to their anatomy and ability to locomote?

They have a foot that is modified into 8 sucker-containing arms that are highly contractible. They also lack a shell, which allows them to swim and drift easier and faster.

   Describe the anatomy of the suckers on an octopus tentacle. What provides the suction?

The suckers on the tentacles are individual muscles that have flexible and soft rims around a central cavity that is able to expand and form suction.

What is unique about the mimic octopus, Thaumoctopus mimicus? Describe this organism’s behavior and why it is cool.

     This octopus is rather unique because it is able to imitate other organisms through camouflage, including the venomous and poisonous ones, in order to evade its predators.

Why are vampire squid described as a monotypic group?

  They are considered a monotypic group because there is only one species.

What mixture of traits from other taxa do vampire squid possess?

They possess the 8 arms, 2 retractile filaments, 2 paddle-like fins from the Octopoda and Myopsida taxa.

      What are filaments? How do these structures relate to the biology of vampire squid?

These structures are webbed arms that are utilized for catching prey items like plankton. These structures relate to a vampire squid’s biology because they have evolved to assist in the animal’s unique ways of living.

What are the major transition(s) in animal evolution associated with Nematodes? Explain how each of these trait(s) is an adaptation that has led to the success of this group.

The major transitions in animal evolution associated with this group is molting, specifically growth by ecdysis.

  What are the common names for nematodes? Where does this name come from?

The common names for this taxa are “round worms,” this name originates from the Greek word of “thread.”

How many species of nematodes are there?  Where do these organisms live?