Enter a player name to begin or load your saved progress.
The electric eel is taxonomically classified within the order Anguilliformes, an order that encompasses all true eels.
Answer: False
Explanation: Contrary to its common name, the electric eel is not a true eel (order Anguilliformes). It is classified within the order Gymnotiformes, making it a type of knifefish.
The genus *Electrophorus* is part of the subfamily Electrophorinae within the family Gymnotidae, placing it among the knifefish order Gymnotiformes.
Answer: True
Explanation: The genus *Electrophorus* is indeed classified within the subfamily Electrophorinae, which belongs to the family Gymnotidae, thus placing it within the order Gymnotiformes, comprising South American knifefish.
The genus name *Electrophorus* is derived from Greek words meaning 'electricity bearer'.
Answer: True
Explanation: The genus name *Electrophorus* originates from the Greek words *ēlektron* (amber, associated with static electricity) and *phérō* (I carry), thus translating to 'electricity bearer'.
Electric eels are closely related to true eels (order Anguilliformes) due to their similar body shape.
Answer: False
Explanation: Despite superficial similarities in body shape, electric eels are not closely related to true eels (order Anguilliformes). They belong to the order Gymnotiformes, making them more closely related to catfish.
The evolutionary lineage of the *Electrophorus* genus is estimated to have separated from *Gymnotus* during the Cretaceous period.
Answer: True
Explanation: Phylogenetic analyses estimate that the evolutionary lineage leading to the genus *Electrophorus* diverged from its sister taxon, *Gymnotus*, during the Cretaceous period.
The three recognized species of *Electrophorus* exhibit significant differences in body shape and coloration.
Answer: False
Explanation: According to the 2019 revision, the three recognized species of *Electrophorus* (*E. electricus*, *E. voltai*, and *E. varii*) do not display significant differences in body shape or coloration.
The species *E. varii* diverged from the lineage leading to *E. electricus* and *E. voltai* approximately 7.1 million years ago.
Answer: True
Explanation: Genetic divergence estimates indicate that the species *Electrophorus varii* separated from the lineage that gave rise to *E. electricus* and *E. voltai* approximately 7.1 million years ago, during the late Miocene epoch.
What is the correct taxonomic classification for the electric eel, placing it within its order and family?
Answer: Order Gymnotiformes, Family Gymnotidae (Knifefish)
Explanation: The electric eel is classified within the order Gymnotiformes and the family Gymnotidae, positioning it among the South American knifefish.
Despite their common name, what is the electric eel's true taxonomic relationship?
Answer: They are a type of knifefish, more related to catfish than true eels.
Explanation: Contrary to their name, electric eels are not true eels but belong to the order Gymnotiformes, classifying them as knifefish and indicating a closer evolutionary relationship to catfish.
What is the etymological meaning of the genus name *Electrophorus*?
Answer: "Electricity bearer"
Explanation: The genus name *Electrophorus* is derived from Greek roots meaning 'electricity bearer,' reflecting the organism's remarkable ability to generate electrical charges.
Electric eels achieve their growth by shedding their skin multiple times a year, similar to reptiles.
Answer: False
Explanation: Electric eels exhibit continuous growth throughout their lives by adding more vertebrae to their spinal column, rather than by shedding their skin.
Electric eels are obligate air-breathers, meaning they must surface to breathe air to survive.
Answer: True
Explanation: Electric eels are obligate air-breathers; they must periodically ascend to the surface to gulp atmospheric air, which is absorbed through specialized tissues in their buccal cavity.
The electric eel's mouth is located on the underside of its snout and opens downwards.
Answer: False
Explanation: The electric eel possesses a superior mouth, situated at the front of its snout and opening upwards.
The electric eel possesses an elongated anal fin used for propulsion, containing over 400 bony rays.
Answer: True
Explanation: The electric eel utilizes its extensive anal fin, which runs along its ventral side and contains more than 400 bony rays, for undulatory propulsion through the water.
The electric eel's gills are highly developed and actively ventilated even when the fish is breathing air.
Answer: False
Explanation: The gills of electric eels are relatively small and are not actively ventilated when the fish is breathing air. Carbon dioxide expulsion primarily occurs through the skin.
Electric eels can survive out of water indefinitely, as long as they are kept in a moist environment.
Answer: False
Explanation: While electric eels can survive out of water for several hours if their skin remains moist, they cannot survive indefinitely due to their reliance on aquatic respiration for certain metabolic processes.
Electric eels have excellent vision, which is their primary sense for detecting prey in murky waters.
Answer: False
Explanation: Electric eels possess poor vision due to their small eyes. They primarily rely on electrolocation, a sense that uses electrical fields, for navigation and prey detection in their environment.
The vital organs of an electric eel are distributed throughout its entire body length, providing protection.
Answer: False
Explanation: The vital organs of an electric eel are concentrated near the anterior portion of its body, occupying approximately 20% of its volume, rather than being distributed throughout its length.
Which of the following describes the primary sensory and ecological characteristics of electric eels?
Answer: Nocturnal, poor eyesight, use electrolocation for navigation and prey detection.
Explanation: Electric eels are primarily nocturnal, possess limited visual acuity, and rely heavily on electrolocation for navigating their environment and locating prey.
How do electric eels facilitate gas exchange when breathing air?
Answer: Using a frilled mucosa in their buccal cavity.
Explanation: Electric eels possess a frilled mucosa lining their buccal cavity, which is richly vascularized and facilitates efficient gas exchange when they surface to breathe air.
What is the arrangement of vital organs in an electric eel's body?
Answer: Clustered near the front, occupying about 20% of the volume.
Explanation: The vital organs of an electric eel are compactly arranged near the anterior end of its body, occupying roughly 20% of the total volume, thereby being protected from the electrical organs.
How does the spinal column of an electric eel change as it grows?
Answer: It continuously adds more vertebrae.
Explanation: As electric eels grow, their spinal columns elongate through the continuous addition of new vertebrae.
The most notable ability of electric eels is their capacity to generate electricity, with some species capable of producing discharges up to 860 volts.
Answer: True
Explanation: Electric eels are renowned for their ability to generate powerful electrical discharges, with certain species documented to produce voltages as high as 860 volts, primarily used for stunning prey.
Most knifefishes in the Gymnotiformes order are strongly electric, similar to electric eels.
Answer: False
Explanation: While electric eels are strongly electric, the majority of other knifefishes within the Gymnotiformes order are weakly electric, utilizing their discharges primarily for electrolocation rather than stunning prey.
*Electrophorus voltai* is known for generating the highest voltage among the electric eel species, reaching up to 860 volts.
Answer: True
Explanation: The species *Electrophorus voltai* has been identified as the most potent bioelectricity generator among electric eels, capable of producing electrical discharges up to 860 volts.
Electric eels possess three pairs of electric organs: the main organ, Hunter's organ, and Sachs' organ.
Answer: True
Explanation: Electric eels are equipped with three pairs of specialized electric organs arranged longitudinally: the main organ, Hunter's organ, and Sachs' organ, which are responsible for generating electrical discharges.
What is the maximum voltage a powerful electrical discharge from an electric eel can reach, as mentioned in the source?
Answer: Up to 860 volts
Explanation: Certain species of electric eels are capable of generating powerful electrical discharges that can reach up to 860 volts.
Which species of electric eel is identified as the strongest living bioelectricity generator, capable of up to 860 volts?
Answer: *Electrophorus voltai*
Explanation: *Electrophorus voltai* is recognized as the most potent bioelectricity generator among electric eel species, with recorded discharges reaching up to 860 volts.
How does most knifefishes differ electrically from the electric eel?
Answer: They are weakly electric and use electricity mainly for electrolocation.
Explanation: Unlike the strongly electric electric eel, most other knifefishes in the Gymnotiformes order are weakly electric, employing their electrical discharges primarily for electrolocation.
What are the two primary types of electrical discharges produced by electric eels, and their main functions?
Answer: Low-voltage for electrolocation, high-voltage for stunning prey/defense.
Explanation: Electric eels produce low-voltage discharges for electrolocation and high-voltage discharges for immobilizing prey and defense against predators.
How do electric eels generate their high voltage output?
Answer: By stacking electrocytes in series.
Explanation: The high voltage output of electric eels is achieved by stacking thousands of electrocytes in series within their electric organs, analogous to connecting multiple batteries in series to increase voltage.
What is the proposed function of Sachs' organ?
Answer: Electrolocation at low voltage.
Explanation: Sachs' organ is believed to function in electrolocation, producing low-voltage electrical discharges (approximately 10 volts) at a frequency of about 25 Hz.
How do electric eels concentrate their electric field to increase its effectiveness on prey?
Answer: By curling their body into a 'U' shape.
Explanation: Electric eels can focus their electrical discharge by adopting a 'U' shape with their body, thereby concentrating the electric field onto the prey and enhancing its stunning effect.
Electric eels are indigenous to the freshwater ecosystems of North America.
Answer: False
Explanation: Electric eels are native to the freshwater environments of South America, not North America.
Electric eels are primarily diurnal, relying heavily on their keen eyesight to navigate and hunt in daylight.
Answer: False
Explanation: Electric eels are predominantly nocturnal and possess poor eyesight. They rely on electrolocation rather than keen vision for navigation and prey detection.
The typical diet of electric eels consists mainly of aquatic plants and algae.
Answer: False
Explanation: Electric eels are carnivorous, primarily feeding on fish, which they immobilize using their electrical discharges.
Male electric eels are typically smaller than females, a characteristic known as sexual dimorphism.
Answer: False
Explanation: In electric eels, sexual dimorphism manifests as males typically being larger than females, particularly in terms of reproductive maturity and overall size.
Some captive electric eel specimens have been documented to live for over 20 years.
Answer: True
Explanation: Observations indicate that electric eels can have a considerable lifespan, with some individuals in captivity documented to live for more than two decades.
Electric eels typically inhabit fast-flowing, clear mountain streams.
Answer: False
Explanation: Electric eels are typically found in slow-moving, muddy waters such as river bottoms and swamps, often in areas with low oxygen levels and dense vegetation.
In which continent are electric eels primarily found?
Answer: South America
Explanation: Electric eels are native to and primarily found in the freshwater ecosystems of South America.
What is the primary food source for electric eels?
Answer: Fish, which they immobilize with electrical discharges
Explanation: The primary diet of electric eels consists of fish, which they incapacitate using their potent electrical discharges before consumption.
How do electric eels achieve continuous growth throughout their lives?
Answer: By adding more vertebrae to their spinal column.
Explanation: Electric eels exhibit continuous growth by adding new vertebrae to their spinal column throughout their lifespan.
What is the observed sexual dimorphism in electric eels?
Answer: Males are larger than females.
Explanation: Sexual dimorphism in electric eels is characterized by males generally attaining larger sizes than females, particularly as they reach reproductive maturity.
What is the documented maximum lifespan for some captive electric eel specimens?
Answer: Over 20 years
Explanation: Certain captive individuals of electric eels have been recorded living for durations exceeding 20 years.
Electric eels typically inhabit which type of aquatic environment?
Answer: Muddy river bottoms and swamps with low oxygen
Explanation: Electric eels are typically found in muddy river bottoms and swamps, environments often characterized by low oxygen levels and limited water flow.
What remarkable defensive behavior have electric eels been observed performing when threatened?
Answer: Leaping out of the water to deliver shocks.
Explanation: When faced with threats, electric eels have been observed to leap from the water, directing their electrical discharges towards potential predators as a formidable defense mechanism.
What role does the male electric eel play during the reproductive season?
Answer: He constructs a nest and protects it and the young.
Explanation: During the reproductive season, the male electric eel constructs a nest, often using saliva, and subsequently provides protection for both the nest and the developing young.
What do young electric eel larvae consume immediately after hatching?
Answer: Unfertilized eggs remaining in the nest
Explanation: Newly hatched electric eel larvae subsist initially on unfertilized eggs that remain within the nest. Their diet shifts to other sources once they reach approximately 9 centimeters in length.
The study of electric eels in 1775 significantly contributed to the understanding of electricity and influenced the invention of the electric battery in 1800.
Answer: True
Explanation: Early investigations into the electrical capabilities of electric eels, notably by John Hunter in 1775, advanced the scientific understanding of electricity and are considered influential precursors to Alessandro Volta's invention of the electric battery.
A significant taxonomic revision in 2019 led to the recognition of three distinct species within the genus *Electrophorus*.
Answer: True
Explanation: In 2019, a comprehensive revision based on genetic, ecological, and anatomical data resulted in the formal recognition of three distinct species within the genus *Electrophorus*, revising the previous understanding of the genus as monotypic.
Carl Linnaeus first described the electric eel in 1766, classifying it in the genus *Electrophorus*.
Answer: False
Explanation: Carl Linnaeus first described the electric eel in 1766, but he initially classified it within the genus *Gymnotus*. The genus *Electrophorus* was established later by Theodore Gill.
The 2019 revision of the genus *Electrophorus* recognized only one species, *Electrophorus electricus*.
Answer: False
Explanation: The 2019 revision of the genus *Electrophorus* resulted in the recognition of three distinct species: *Electrophorus electricus*, *Electrophorus voltai*, and *Electrophorus varii*.
In 2019, researchers primarily used anatomical comparisons to understand the phylogenetic relationships of electric eels.
Answer: False
Explanation: The 2019 study investigating the phylogenetic relationships of electric eels primarily utilized analysis of mitochondrial DNA, rather than solely anatomical comparisons.
How did early scientific investigations into electric eels influence technological development?
Answer: They contributed to the understanding of electricity and the invention of the electric battery.
Explanation: Early studies on electric eels advanced the comprehension of electrical phenomena and significantly influenced the subsequent invention of the electric battery.
According to the 2019 revision, how many distinct species are now recognized within the genus *Electrophorus*?
Answer: Three species
Explanation: The taxonomic revision conducted in 2019 recognized three distinct species within the genus *Electrophorus*.
Who first described the electric eel, and what was the original genus assigned?
Answer: Carl Linnaeus, *Gymnotus*
Explanation: Carl Linnaeus provided the initial description of the electric eel in 1766, classifying it under the genus *Gymnotus*.
What method was primarily used in the 2019 study to analyze the evolutionary relationships of electric eels?
Answer: Analysis of mitochondrial DNA
Explanation: The 2019 research on electric eel phylogeny predominantly employed the analysis of mitochondrial DNA to ascertain their evolutionary relationships.
Which of the following is NOT a recognized species within the genus *Electrophorus* following the 2019 revision?
Answer: *Electrophorus electricus novus*
Explanation: Following the 2019 revision, the recognized species are *Electrophorus electricus*, *Electrophorus varii*, and *Electrophorus voltai*. '*Electrophorus electricus novus*' is not a recognized species.
What was Carl Sachs' contribution to the study of electric eels?
Answer: He discovered and described Sachs' organ.
Explanation: Carl Sachs is credited with the discovery and description of Sachs' organ, a significant contribution to the understanding of electric eel physiology.
What did Hao Sun and colleagues develop in 2016 that mimics electric eels?
Answer: Flexible fiber electrochemical capacitors
Explanation: In 2016, Hao Sun and his research team developed flexible fiber electrochemical capacitors that emulate the electrical output characteristics of electric eels.