Marine Vertebrate Zoology Practice Flashcards

A set of 200 question-and-answer flashcards covering systematics, anatomy, physiology, behavior, and conservation of marine fish, reptiles, and mammals.

What is the relationship between taxonomy and systematics?

Taxonomy is a branch of systematics focused on identifying, describing, naming, and classifying organisms, whereas systematics is the broader study of biological diversity and evolutionary relationships (phylogeny).

What are meristic characters?

Any countable structure in an organism, such as the number of scales, petals, or toes.

What do morphometric characters refer to?

Measurable structures and their ratios, such as fin length, head length, and eye diameter.

What is an apomorphy?

A recently evolved, derived, or advanced character.

What term describes an ancestral, primitive, or generalized character?

Plesiomorphy.

What is a synapomorphy?

A shared derived character used to diagnose monophyletic groups or clades.

Why are symplesiomorphies not useful for constructing phylogenetic classifications?

Because shared ancestral characters may be retained in a wide variety of distantly related taxa.

What is an autapomorphy?

A specialized character present in only a single taxon, which is not useful for constructing phylogenetic trees.

Define homoplasy.

Shared, independently derived similarities such as parallelisms, convergences, or secondary losses that do not reflect evolutionary history.

What are the three main groups of marine mammals mentioned in the notes?

Cetacea, Carnivora (Pinnipeds), and Sirenia.

What constitutes a monophyletic group on a cladogram?

A group in which two or more species all descended from a single common ancestor.

What is a paraphyletic group?

A group that contains some, but not all, of the species derived from the most recent common ancestor.

Define a polyphyletic group.

A group where two or more species do not share a recent common ancestor, which currently researchers agree on avoiding.

What are the two parts of a scientific name according to binomial nomenclature?

The Genus, which is capitalized, and the species, which is not.

What are the four primary reasons for changing an organism's scientific name?

Splitting a species, lumping two species, changes in classification (e.g., genus change), or discovery of an earlier name via the Principle of Priority.

According to the transcript, how many living species of fish were there (updated to the current count)?

Over 34,000 species.

Where is the greatest diversity of marine fish found?

In the tropics, particularly the Indo-West Pacific region.

What are the three classes of fish mentioned in general systematics?

Jawless vertebrates (Agnatha), Cartilaginous fishes (Chondrichthyes), and Bony fishes (Osteichthyes).

What are two examples of Jawless vertebrates?

Myxine (hagfish) and Cephalaspidomorphi (lampreys).

What are the two groups included under Bony fishes (Osteichthyes)?

Actinopterygii (ray-finned fishes) and Sarcopterygii (lobe-finned fishes).

What is a distinctive feature of the hagfish (Myxine) mouth?

It is a round opening with horny teeth.

What does the term 'anadromous' mean in the context of lampreys?

They spawn and lay eggs in fresh water, such as streams and rivers, but live much of their adult lives in the sea.

What is the primary material of the skeleton in Chondrichthyes?

Cartilage (no true bones).

What is the function of claspers in cartilaginous fishes?

They are specialized organs in males for internal fertilization.

Which subclass of cartilaginous fish includes sharks, skates, and rays?

Elasmobranchii.

What organ do Elasmobranchii use for buoyancy instead of a gas bladder?

Large, buoyant livers.

What characterizes the subclass Holocephali (chimaeras)?

A single gill flap covering four internal gill openings, no spiracle, and the laying of eggs with a horny shell.

Which fish is described as a 'long-lost survivor from the Age of dinosaurs'?

The Coelacanth (Latimeria chalumnae).

What are the two main regions of the fish skull?

The neurocranium (upper) and the branchiocranium (lower).

What are the four regions of the neurocranium?

Ethmoid, orbital, otic, and basicranial.

Define precaudal vertebrae.

Anterior vertebrae extending to the end of the body cavity that bear ribs.

What defines caudal vertebrae?

Posterior vertebrae beginning with the first vertebra bearing an elongate haemal spine.

What is a protocercal tail?

A primitive undifferentiated caudal fin found in adult lancelets, hagfishes, and lampreys.

What is a heterocercal tail?

An unequal-lobed tail found in Chondrichthyes and primitive osteichthyans.

Define a homocercal tail.

An equal-lobed tail found in most teleosts.

What is a hypocercal tail?

A tail with a larger lower lobe into which the vertebral column is bent downwards.

In Osteichthyans, what replace the ceratotrichia during development?

Lepidotrichia, which are bony supporting elements derived from scales.

What are the five basic types of scales?

Placoid, cosmoid, ganoid, cycloid, and ctenoid.

Specify the structure of a placoid scale.

A flattened basal plate embedded in the dermis with a posteriorly projecting spine made of dentine and covered by enameloid.

What is unique about the growth of placoid scales?

They do not increase in size with growth; instead, new scales are added between older ones.

What layers compose cosmoid scales?

Two basal layers of bone (isopedine and cancellous bone), a layer of cosmine, and a thin superficial layer of vitrodentine.

What is ganoine?

An inorganic bone salt secreted by the dermis that replaces vitrodentine in ganoid scales.

What is the difference between cycloid and ctenoid scales?

Ctenoid scales have ctenii (teeth) on the posterior border, whereas cycloid scales lack them and have a smooth margin.

What does Williston's Law state?

Organs in an organism tend to reduce in number while undergoing increased functional specialization.

What are the three types of fish muscle?

Striated (skeletal), smooth (involuntary/gut), and cardiac (heart).

What are epaxial muscles?

The upper pair of skeletal muscles in jawed fishes, separated by the horizontal septum.

What are hypaxial muscles?

The lower pair of skeletal muscles in jawed fishes.

Describe the fish circulatory circuit.

A single-circuit system where blood flows from the heart to the gills, then to the body, and back to the heart.

Name the four main parts of the fish heart.

Sinus venosus, atrium, ventricle, and conus arteriosus.

Which arteries bring oxygen-deficient blood to the gills?

Afferent branchial arteries.

What is the longest artery in a fish’s body?

The dorsal aorta.

What is the function of the spiral valve in a shark's intestine?

To increase the absorptive surface of the intestine without increasing its volume.

What is a cloaca?

A small chamber where the digestive, reproductive, and urinary tracts end in a single external opening.

What is the hepatopancreas?

An organ formed when the pancreas is incorporated into the liver, found in most spiny-rayed teleosts.

Define oviparity.

A strategy where the female lays eggs containing embryos nourished by a yolk sac.

Define ovoviviparity (aplacental viviparity).

The female produces young nourished in the uterus solely by a yolk sac, with no placenta, and live young are released.

What differentiates placental viviparity from ovoviviparity?

In placental viviparity, the young are nourished in the uterus by a placenta formed from a modified yolk sac attached to the uterine wall.

What has the largest brain relative to body weight among fishes?

Elephant fishes (Mormyridae), with ratios from $\frac{1}{52}$ to $\frac{1}{82}$.

What are the five parts of the fish brain?

Telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon.

What is the primary function of the metencephalon in fish?

Maintaining muscular tone and equilibrium in swimming via the cerebellum.

What are the four types of fish senses?

Chemoreception, mechanoreception, photoreception, and electroreception.

What is the tapetum lucidum?

A structure under the retina that reflects light back to restimulate photoreceptors, increasing eye sensitivity.

What is the nictitating membrane?

A movable 'third eyelid' found in some sharks for protection while feeding.

What are ampullae of Lorenzini?

Small organs containing sensory hair cells and conductive jelly used by cartilaginous fishes to detect electrical currents from prey.

How do gills extract oxygen and release carbon dioxide?

Through highly vascular membranes called gill lamellae.

What is countercurrent flow in fish respiration?

Blood flows through secondary lamellae in the opposite direction of water flow to maximize oxygen diffusion efficiency.

What is ram ventilation?

A process where fast-swimming fish channel water to the gills by swimming with an open mouth.

Define regional endothermy in fishes.

A condition where some species maintain a higher body temperature than seawater due to a heat-retaining system.

What is the rete mirabile?

A complicated network of arteries and veins that transfers metabolic heat into the blood or aids in gas exchange.

Name the gases commonly found in a fish's gas bladder.

Carbon dioxide, oxygen, and nitrogen.

What is the difference between physostomous and physoclistous fishes?

Physostomous fishes retain the pneumatic duct connection between the gas bladder and gut, while physoclistous fishes lack it as adults.

How is gas introduced into the bladder of physoclistous fishes?

Through a gas gland that excretes lactic acid, causing hemoglobin to release oxygen which then diffuses into the bladder.

What is the 'oval' in a fish's gas bladder?

A thin, highly vascularized area used for the resorption of gases.

Define barotrauma in fish.

Internal damage occurring when a fish is hauled to the surface, causing the gas bladder to expand as pressure decreases.

Which organ provides buoyancy for the basking shark?

A huge oily liver accounting for up to $25\%$ of its body weight.

What are the functional units of the pronephros kidney?

A glomus supplied by the dorsal aorta and a ciliated nephrostome leading to a pronephric tubule.

What constitutes a Malpighian body?

Bowman’s capsule together with the internal glomerulus.

How do marine bony fishes compensate for dehydration?

By drinking seawater and excreting a low volume of highly concentrated urine.

How do freshwater bony fishes avoid waterlogging?

They do not drink water and produce copious amounts of highly diluted urine.

Why do sharks not need to drink seawater?

Their tissue salt content is higher than seawater because they retain urea, so water diffuses in naturally via osmosis.

What allows Ice-fish (Channichthyidae) to survive water at $-2\,^\circ\text{C}$?

They have evolved antifreeze proteins and lack hemoglobin as adults.

Name the four lineages of living marine reptiles.

Sea turtles, marine iguanas, sea snakes, and sea kraits.

What two parts make up a turtle's shell?

The carapace (upper shell) and the plastron (underside).

Which scutes connect the carapace to the plastron?

Inframarginal scutes, forming the bridge.

What is the largest living turtle?

The Leatherback turtle (Dermochelys coriacea).

What is a unique physical feature of the Leatherback turtle's shell?

It lacks a bony shell; its carapace is covered with skin and oily flesh, with seven distinct ridges.

Which sea turtle is the largest living hard-shelled turtle?

The Loggerhead sea turtle (Caretta caretta).

What identifies the Green turtle (Chelonia mydas) carapace?

It has $4$ pairs of costal scutes (rather than $5$) and scutes that never overlap.

Why might a Hawksbill turtle's (Eretmochelys imbricata) flesh be toxic?

Due to its consumption of venomous cnidarians.

What is the smallest species of sea turtle?

The Atlantic ridley turtle (Lepidochelys kempii), also known as Kemp’s ridley.

Where do all marine turtles lay their eggs?

In the terrestrial zone (nesting beaches).

Define the neritic zone.

The nearshore marine environment where water depths do not exceed $200\,m$.

What is the primary diet of the Galápagos marine iguana?

Algae.

What are the main differences between sea snakes and sea kraits?

Sea snakes are viviparous and have reduced ventral scales, while sea kraits are oviparous and have wide ventral scales for moving on land.

What is the oldest group of marine reptiles mentioned?

Mesosaurs, appearing during the Permian ($280\text{--}248$ MYA).

Which extinct marine reptiles looked like dolphins?

Ichthyosauria.

Why are most marine reptiles restricted to tropical and subtropical areas?

They are ectothermic and struggle to maintain a minimum body temperature of $18\,^\circ\text{C}$ in cold waters.

What are three reptilian adaptations useful for aquatic life?

Ectothermy, capacity for anaerobic metabolism, and tolerance of acid-base disturbance.

What are salt glands and which ones do sea turtles have?

Organs that excrete excess salt ($Na+$ and $Cl-$); sea turtles have lacrimal glands.

How do some sea snakes supplement pulmonary respiration?

Through cutaneous respiration (breathing through their skin), which accounts for about $20\%$ of oxygen uptake.