Biol 121a Final exam Chapter 10-13

The foot is a muscular structure used for locomotion and anchoring. It varies in shape and function across different mollusc classes.

Visceral mass: The central section of the body that contains the internal organs, such as the digestive, excretory, and reproductive systems. It is typically covered by the mantle, which secretes the shell in many molluscs.

The mantle is a significant part of a mollusc's anatomy. It is a layer of tissue that covers the visceral mass and is responsible for secreting the shell in many molluscs. The mantle also forms a cavity that houses the gills or lungs, playing a crucial role in respiration and excretion.

The shell is a hard, protective outer layer secreted by the mantle in many molluscs. It provides support and protection for the soft body parts of the organism. The shell is typically composed of calcium carbonate and can vary greatly in shape, size, and color among different mollusc species.

The mantle cavity is a central feature in molluscs. It is a space formed by the mantle that houses the gills or lungs and serves as a chamber for excretion and respiration. This cavity plays a crucial role in the mollusc's ability to exchange gases and expel waste products.

Ctenidia are specialized gill structures found in molluscs. They are used for respiration and, in some species, for filter-feeding. Ctenidia are typically located within the mantle cavity and are composed of numerous filaments that increase the surface area for gas exchange.

The osphradium is a chemosensory organ found in the mantle cavity of many molluscs. It is used to monitor the quality of water entering the mantle cavity, detecting silt, food particles, and other chemical cues. This organ is typically located near the ctenidia (gills) and plays a crucial role in the mollusc's ability to sense its environment.

Rhinophores are sensory organs found in some molluscs, particularly in sea slugs (nudibranchs). These structures are located on the head and resemble antennae. Rhinophores are used to detect chemical signals in the water, helping the mollusc navigate its environment and locate food or mates.

The radula is a specialized feeding organ found in molluscs. It is a ribbon-like structure covered with tiny, chitinous teeth that molluscs use to scrape or cut food before ingestion. The radula is often compared to a tongue and is essential for the feeding process in many mollusc species.

The girdle is a structure found in chitons, a type of mollusc. It is a tough, flexible band that surrounds the chiton's shell plates, providing protection and aiding in movement. The girdle can also have spines, scales, or bristles, depending on the species.

Shell valves are the individual, hinged parts of a bivalve mollusc's shell. These valves are typically symmetrical and are joined together by a flexible ligament. They protect the soft body of the mollusc and can open and close to allow the animal to feed and respire.

A trochophore is a type of larval stage found in some marine invertebrates, including molluscs and annelids. It is characterized by its spherical shape, ciliated bands for swimming, and a simple digestive system. The trochophore stage is crucial for the dispersal and development of these organisms.

Glochidia are the larval stage of freshwater mussels (bivalves). These larvae are parasitic and attach themselves to the gills or fins of fish, where they develop into juvenile mussels. This stage is crucial for the dispersal and life cycle of freshwater mussels.

A veliger is a larval stage in the life cycle of certain molluscs, such as snails and bivalves. It follows the trochophore stage and is characterized by the development of a ciliated swimming organ called the velum. The veliger stage is crucial for the dispersal and development of these organisms.

A ligament in molluscs is a flexible, fibrous tissue that connects the two shell valves in bivalves. It acts as a hinge, allowing the valves to open and close while maintaining their alignment. The ligament plays a crucial role in the movement and protection of the mollusc.

The adductor muscle in molluscs is a strong muscle that connects the two shell valves in bivalves. It is responsible for closing the shell tightly, providing protection against predators and environmental stressors. When the muscle relaxes, the shell opens, allowing the mollusc to feed and respire.

The hinge in bivalves, is the flexible, jointed area where the two shell valves are connected. It allows the valves to open and close, facilitating feeding and respiration while providing protection to the mollusc's soft body.

A siphon is a tubular structure found in some molluscs, such as bivalves and cephalopods. It is used for drawing in and expelling water, which aids in respiration, feeding, and locomotion. In cephalopods, the siphon also plays a role in jet propulsion, allowing them to move quickly through the water.

Byssal threads are strong, silky fibers produced by certain bivalve molluscs, such as mussels. These threads are used to attach the mollusc to surfaces like rocks, pilings, or other substrates in their aquatic environments. Byssal threads provide stability and protection against strong currents and predators.

Captacula are specialized, slender tentacles found in tusk shells (Scaphopoda). These tentacles serve as sensory and food-catching organs, helping the mollusc to detect and capture small organisms from the surrounding sediment.

Torsion is a process in the development of gastropod molluscs where the visceral mass, mantle, and shell rotate 180 degrees. This results in the anus and mantle cavity being positioned above the head. Torsion is unique to gastropods and has significant implications for their anatomy and behavior.

The operculum is a structure found in some molluscs, particularly in snails. In molluscs, it is a hard, protective plate that covers the opening of the shell when the animal retracts inside. This helps protect the mollusc from predators and desiccation. In fish, the operculum is a bony flap that covers and protects the gills.

Tentacles are elongated, flexible appendages found in various molluscs, such as cephalopods (e.g., octopuses and squids). They are used for a variety of functions, including sensing the environment, capturing prey, and manipulating objects. Tentacles are often equipped with suckers or hooks to aid in these tasks.

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Arms in molluscs, particularly in cephalopods like octopuses and squids, are flexible appendages used for a variety of functions. These include capturing prey, manipulating objects, and sensing the environment. Unlike tentacles, arms typically have suckers along their entire length, providing a strong grip and enhanced dexterity.

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Gill hearts, also known as branchial hearts, are specialized structures found in cephalopods, such as octopuses and squids. These hearts are located near the gills and are responsible for pumping blood through the gills for oxygenation. Cephalopods have a unique circulatory system with three hearts: two gill hearts and one systemic heart. The gill hearts ensure efficient oxygenation of the blood before it is circulated to the rest of the body by the systemic heart.

The systemic heart is the main heart in cephalopods, such as octopuses and squids. It pumps oxygenated blood from the gills to the rest of the body. Cephalopods have a unique circulatory system with three hearts: two gill hearts that pump blood through the gills for oxygenation, and the systemic heart that circulates the oxygenated blood throughout the body. This efficient system supports their active lifestyle and high metabolic demands.

Jet Propulsion: Cephalopods use their mantle cavity for jet propulsion, allowing them to move quickly through the water.

Muscular Mantle: Their mantle is highly muscular, aiding in movement.

Three Hearts: Cephalopods have two gill hearts and one systemic heart for efficient blood circulation.

Advanced Sensory Organs: They have more developed sensory organs in the mantle cavity.

Ink Sac: Many cephalopods have an ink sac for defense, which is not found in other molluscs

The funnel, also known as the siphon, is a key structure in cephalopods like squids and octopuses. It is a muscular tube used for jet propulsion, allowing these animals to move quickly through the water. The funnel expels water forcefully, enabling rapid movement and aiding in respiration and waste expulsion. This adaptation is unique to cephalopods and plays a crucial role in their mobility and survival.

Hemocyanin is a copper-containing protein found in the blood of some molluscs and arthropods. It serves a similar function to hemoglobin in vertebrates, transporting oxygen throughout the body. Hemocyanin is blue when oxygenated, giving the blood of these animals a distinctive blue color. This protein is particularly efficient at binding oxygen in cold, low-oxygen environments, making it well-suited for the habitats of many molluscs and arthropods.

The pen, or gladius, is a thin, internal shell in cephalopods like squids. It provides support and helps maintain the animal's shape, aiding in buoyancy and movement.

The nautilus shell is a spiral, chambered shell that helps the nautilus regulate its buoyancy by adjusting the gas and liquid within the chambers.

Setae are bristle-like structures found in various invertebrates, including annelid worms and some molluscs. They are used for locomotion, sensation, and anchoring the animal in its environment. Setae can vary in size, shape, and function depending on the species and their specific needs.

Metamerism is the segmentation of an organism's body into a series of repetitive segments, called metameres. This feature is seen in various animal groups, including annelid worms, arthropods, and some molluscs. Metamerism allows for greater flexibility and specialization of body regions, contributing to the complexity and adaptability of these organisms.

Segmentation is the division of an organism's body into repetitive segments, called metameres. This feature is seen in various animal groups, including annelid worms, arthropods, and some molluscs. Segmentation allows for greater flexibility and specialization of body regions, contributing to the complexity and adaptability of these organisms.

Dorsal and ventral blood vessels are key components of the circulatory system in many invertebrates, including annelid worms. The **dorsal blood vessel** runs along the back (dorsal side) of the organism and typically carries blood toward the head. The **ventral blood vessel** runs along the belly (ventral side) and usually carries blood toward the tail.

The ventral nerve cord is a major nerve cord in many invertebrates, running along the belly side and coordinating movement and sensory information.

Metanephridia are excretory organs found in many invertebrates, including annelid worms. They function in osmoregulation and waste removal, filtering body fluids and expelling waste products from the body. Each segment of an annelid typically contains a pair of metanephridia, which help maintain the organism's internal environment.

The prostomium is the anterior (front) part of an annelid worm's body, located before the mouth. It often contains sensory organs, such as antennae and eyes, and helps the worm sense its environment and navigate through soil or water.

The peristomium is the second segment of an annelid worm's body, located just behind the prostomium. It surrounds the mouth and often bears sensory structures, such as tentacles or palps, which help the worm interact with its environment and gather food.

Parapodia are paired, fleshy appendages found in some annelid worms, particularly polychaetes. They are used for locomotion and respiration, often bearing bristles called setae that help the worm move and interact with its environment.

The crop is a storage organ found in some annelid worms, such as earthworms. It temporarily holds food before it is passed to the gizzard for grinding and digestion.

The clitellum is a thickened, glandular section of the body found in some annelid worms, such as earthworms. It plays a crucial role in reproduction by secreting a mucus cocoon that encases the worm's eggs and sperm, facilitating fertilization and protecting the developing embryos.

Hematophagous organisms are those that feed on blood. This term is often used to describe certain insects, such as mosquitoes, and other animals like leeches, which have specialized adaptations for consuming blood from their hosts.

Ecdysis is the process of shedding or molting the outer cuticle layer in invertebrates, such as arthropods and nematodes. This allows the organism to grow and develop a new, larger exoskeleton.

Ecdysozoa is a group of protostome animals that includes arthropods, nematodes, and several other phyla. These animals are characterized by their ability to molt, or shed their exoskeleton, in a process called ecdysis. This group is highly diverse and includes many well-known organisms, such as insects, spiders, and roundworms.

The cuticle is a protective outer layer found in many invertebrates, including arthropods and nematodes. It provides structural support and protection against environmental hazards. The cuticle is often composed of chitin and proteins, and it plays a crucial role in the molting process, allowing these organisms to grow by shedding their old cuticle and forming a new one.

Eutely is a condition in which an organism has a fixed number of cells in its body throughout its life. This means that growth occurs by cell enlargement rather than cell division. It is commonly observed in certain nematodes and other microscopic organisms.

Parthenogenesis is a form of asexual reproduction where an organism develops from an unfertilized egg resulting in a identical clone

Caenorhabditis elegans

An exoskeleton is a rigid external covering that provides support and protection to certain invertebrates, like arthropods.

Chitin is a tough, flexible polysaccharide that forms the main component of the exoskeletons of arthropods, such as insects and crustaceans. It provides structural support and protection.

Jointed appendages are limbs with joints, found in arthropods like insects, spiders, and crustaceans. These joints allow for a wide range of movement and flexibility, enabling these animals to perform various tasks such as walking, grasping, and feeding.

Arachnida is a class of joint-legged invertebrates that includes spiders, scorpions, ticks, and mites. These creatures typically have eight legs and no antennae. They are known for their diverse adaptations, such as silk production in spiders and venomous stingers in scorpions. Arachnids play important roles in ecosystems as predators and decomposers.

Merostomata is a class of arthropods that includes horseshoe crabs. These ancient creatures have a hard exoskeleton, a pair of compound eyes, and a long, spike-like tail called a telson. They are known for their blue blood, which contains a substance used in medical testing to detect bacterial endotoxins.

Pycnogonida, also known as sea spiders, are marine arthropods that have long legs in proportion to their small bodies. They are found in oceans worldwide and are known for their unique appearance and feeding habits, often preying on soft-bodied invertebrates like sea anemones and sponges.

Chilopoda is a class of arthropods commonly known as centipedes. These creatures are characterized by their elongated, segmented bodies, with each segment typically bearing one pair of legs. Centipedes are predatory and have venomous claws called forcipules, which they use to capture and subdue their prey. They are found in various habitats worldwide and play a role in controlling insect populations.

Diplopoda, commonly known as millipedes, are a class of arthropods characterized by their elongated, segmented bodies with two pairs of legs per segment. Unlike centipedes, millipedes are detritivores, meaning they feed on decaying organic matter, playing a crucial role in breaking down and recycling nutrients in the ecosystem.

Hexapoda includes insects and their close relatives. These creatures are characterized by having three pairs of legs, a three-part body (head, thorax, and abdomen), and usually one or two pairs of wings. Hexapods are incredibly diverse and play essential roles in ecosystems, such as pollination, decomposition, and serving as a food source for other animals.

Malacostraca is a large class of crustaceans that includes familiar animals like crabs, lobsters, shrimp, and krill. These creatures typically have a segmented body divided into three main parts: the head, thorax, and abdomen. They play important roles in aquatic ecosystems and are also significant in human cuisine and industry.

Thecostraca is a class of crustaceans that includes barnacles. These marine organisms are known for their hard calcareous plates that protect their bodies. They attach themselves to various surfaces, such as rocks, ship hulls, and even other animals, and filter feed by extending their feathery appendages to capture plankton from the water.

Segmentation is the division of an organism's body into repetitive segments. This feature is seen in various animal groups, including annelids, arthropods, and chordates. It allows for greater flexibility and specialization of body parts, contributing to the complexity and adaptability of these organisms.

Tagmatization is the evolutionary process in which the segments of an organism's body become specialized into distinct regions, or tagmata, each with specific functions. This is commonly seen in arthropods, where the body is divided into regions such as the head, thorax, and abdomen, each adapted for different tasks like feeding, locomotion, and reproduction.

Tagmata are specialized body regions in segmented animals, particularly arthropods, resulting from the evolutionary process of tagmatization. These regions, such as the head, thorax, and abdomen in insects, are adapted for specific functions like feeding, locomotion, and reproduction.

The head is the anterior part of an organism's body, typically housing sensory organs like eyes and antennae, as well as the brain and mouthparts. In arthropods, the head is one of the specialized body regions, or tagmata, resulting from tagmatization.

The thorax is the middle section of an arthropod's body, located between the head and the abdomen. It typically bears the legs and wings, playing a crucial role in locomotion and movement.

The abdomen is the posterior part of an arthropod's body, following the thorax. It contains vital organs and structures related to digestion, excretion, and reproduction. In insects, the abdomen often has segments and may bear appendages like cerci or ovipositors.

The trunk is the main body region of an arthropod, excluding the head and appendages. It typically includes the thorax and abdomen, housing vital organs and structures necessary for the organism's survival and function.

The prosoma, also known as the cephalothorax, is the anterior part of an arachnid's body. It combines the head and thorax into a single unit, housing the eyes, mouthparts, and legs. This structure is crucial for the arachnid's sensory and locomotion functions.

The opisthosoma, also known as the abdomen, is the posterior part of an arachnid's body. It contains vital organs related to digestion, reproduction, and excretion. In spiders, the opisthosoma is connected to the prosoma (cephalothorax) by a narrow pedicel, allowing flexibility and movement.

The cephalothorax, also known as the prosoma, is a body region in some arthropods, such as arachnids and crustaceans. It combines the head and thorax into a single unit, housing the eyes, mouthparts, and legs. This structure is crucial for sensory and locomotion functions.

The pleon is the posterior part of the body in some crustaceans, such as shrimp and lobsters. It is equivalent to the abdomen and typically contains the swimmerets, which are appendages used for swimming and, in some species, for carrying eggs.

A hemocoel is the primary body cavity in arthropods and some molluscs, where blood circulates. Unlike a closed circulatory system, the hemocoel allows blood to flow freely around the organs, providing nutrients and removing waste. This open circulatory system is a key feature of these invertebrates.

The epicuticle is the outermost layer of an arthropod's exoskeleton. It is a thin, waxy layer that provides protection against water loss and environmental damage. This layer is crucial for maintaining the integrity and functionality of the exoskeleton.

The procuticle is a thick, inner layer of an arthropod's exoskeleton, lying beneath the epicuticle. It is composed of chitin and proteins, providing strength and flexibility. The procuticle is further divided into two layers: the exocuticle, which is hardened and provides rigidity, and the endocuticle, which remains more flexible.

Ocelli, also known as simple eyes, are small, light-sensitive organs found in many arthropods, including insects and spiders. Unlike compound eyes, which are made up of many individual units called ommatidia, ocelli consist of a single lens that can detect changes in light intensity. They help the organism with basic light detection and orientation.

Compound eyes are complex visual organs found in many arthropods, such as insects and crustaceans. They consist of numerous small units called ommatidia, each with its own lens and photoreceptor cells. This structure allows for a wide field of view and the ability to detect fast movements, making compound eyes highly effective for navigating and responding to their environment.

Ommatidia are the individual units that make up the compound eyes of arthropods, such as insects and crustaceans. Each ommatidium consists of a lens, photoreceptor cells, and pigment cells, allowing it to capture a portion of the visual field. Together, the ommatidia create a mosaic-like image, providing the organism with a wide field of view and the ability to detect fast movements.

Antennae are sensory appendages found on the heads of many arthropods, including insects and crustaceans. They are used for detecting various environmental stimuli, such as touch, smell, and sometimes sound. Antennae play a crucial role in helping these organisms navigate their surroundings, find food, and communicate with others.

Mandibles are a pair of mouthparts found in many arthropods, including insects and crustaceans. They are used for biting, cutting, and holding food. In some species, mandibles are also used for defense or manipulating objects. They are a crucial part of the feeding mechanism in these animals.

Chelicerae are a pair of appendages found near the mouth of arachnids, such as spiders and scorpions. These structures are often modified into fangs or pincers and are used for grasping, piercing, or injecting venom into prey. Chelicerae play a crucial role in the feeding and defense mechanisms of these creatures.

Pedipalps are a pair of appendages found near the mouth of arachnids, such as spiders and scorpions. These structures are often used for sensory purposes, manipulating prey.

Ovigers are specialized appendages found in some arthropods, particularly sea spiders (class Pycnogonida). These structures are primarily used for grooming and carrying eggs. In male sea spiders, ovigers play a crucial role in egg brooding, with males carrying the fertilized eggs until they hatch. They are located on the ventral side of the body, between the second and third pairs of walking legs.

Maxillipeds are appendages found in crustaceans, such as crabs and lobsters. They are located near the mouth and are used for handling food. Maxillipeds are adapted for various functions, including sensing, manipulating, and processing food items before they enter the mouth.

Maxillae are paired mouthparts found in many arthropods, including insects and crustaceans. They are located behind the mandibles and are used for manipulating and processing food.

Chelipeds are the large, claw-bearing appendages found in some crustaceans, such as crabs and lobsters. These powerful claws are used for defense, capturing prey, and manipulating objects.

Walking legs are appendages found in many arthropods, including insects, crustaceans, and arachnids. These legs are primarily used for locomotion, allowing the organism to move efficiently in its environment.

Swimmerets, also known as pleopods, are small, paired appendages found on the underside of the abdomen in many crustaceans, such as shrimp, lobsters, and crayfish. These structures are primarily used for swimming, but they also play a role in reproduction. In some species, female crustaceans use swimmerets to carry and aerate their eggs, ensuring proper development.

Uropods are the paired appendages found at the rear end of the abdomen in many crustaceans, such as shrimp, lobsters, and crayfish. These structures are often used for swimming and steering, helping the animal to move backward quickly. Uropods, along with the telson, form the tail fan.

A partially-closed circulatory system is a type of circulatory system found in some invertebrates, such as certain molluscs and arthropods. In this system, blood is pumped by the heart through vessels, but it also flows freely through body cavities, or hemocoels, where it bathes the organs directly.

Malpighian tubules are excretory organs found in many arthropods, including insects and some arachnids. These tubules are responsible for removing waste products from the hemolymph (the arthropod equivalent of blood) and regulating water and ion balance.

Book gills are respiratory structures found in horseshoe crabs and some other arthropods. They consist of numerous thin, leaf-like membranes arranged in stacks, resembling the pages of a book. These membranes provide a large surface area for gas exchange, allowing the organism to efficiently extract oxygen from the water and expel carbon dioxide. Book gills are located on the ventral side of the animal and play a crucial role in their respiration.

Book lungs are respiratory structures found in some arachnids, such as spiders and scorpions. They consist of stacked, leaf-like plates that provide a large surface area for gas exchange. These plates are enclosed in an internal chamber, with openings called spiracles that allow air to enter and exit.

Spiracles are small openings found on the surface of some arthropods, such as insects and arachnids. These openings are part of the respiratory system and allow air to enter and exit the body. Spiracles lead to a network of tubes called tracheae, which transport oxygen directly to the tissues and remove carbon dioxide. This system enables efficient gas exchange, crucial for the organism's survival.

In arthropods, the trachea is a network of small tubes that facilitate respiration. These tubes branch throughout the body, delivering oxygen directly to tissues and cells while removing carbon dioxide. The tracheal system is highly efficient, allowing for effective gas exchange without the need for a circulatory system to transport respiratory gases.