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Crustaceans Trivia Questions and Answers

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Related Questions & Answers:   Invertebrates    Insects    Arachnids   

1. The robber crab gets its name because of its alleged habit of stealing which fruit, from which it gets an alternate name?


Answer: Coconut

Interesting Information:
The robber crab, also known as the coconut crab, is known for taking coconuts. It is commonly believed that it cracks them open with its claws, but this is not true as a robber crab is not strong enough to do so. Instead, the robber crab pierces its claws into the coconut and drops it from a high tree or eats coconuts that split open naturally. Difficulty: Hard.

From Quiz: The Selfish Shellfish
 
Some incorrect choices:
Banana, Papaya, Durian

2. What crab lives on hydro thermal vents at a depth of up to 7,200 feet?


Answer: Yeti crab

Interesting Information:
Thought to be blind, it lacks pigment and has hairy pincers. Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
Blue crab, Alaskan king crab, Soft shell crab

3. What is the name for the study of crustaceans?


Answer: carcinology

Interesting Information:
From thefreedictionary.com: "the department of Zoology which treats of the Crustacea (lobsters, crabs, etc.)"

Other names for the same study include crustalogy, crustaceology, and malacostracology.

Difficulty: Hard.

From Quiz: Friendly Crustaceans Under the Sea
 
Some incorrect choices:
anthropology, gastroenterology, entomology

4. What is the scientific name of the decorator crab?


Answer: Oregonia gracilis

Interesting Information:
The scientific name comes from the Greek word "Orego" which means to stretch or reach, and the Latin word, "Gracilis" meaning slender, thin or simple. Plagusia chabrus is the scientific name for the red rock crab. Ovalipes australiensis is the scientific name for the sand crab and Mictyris platycheles which is the scientific name for the soldier crab. Difficulty: Hard.

From Quiz: The Decorator Crab
 
Some incorrect choices:
Plagusia chabrus, Ovalipes australiensis, Mictyris platycheles

5. The blue crab, while a favorite of Marylanders, is actually widespread along the North American coast ranging from as far north as Massachusetts to as far south and west as Texas. What area produces over 50% of the blue crab harvest every year?


Answer: The Chesapeake Bay

Interesting Information:
The silty, less saline waters of the Chesapeake are ideal for blue crabs to scavenge, hide from predators, and mate. Smaller populations of blue crabs can be found outside of the U.S. ranging from Nova Scotia to Argentina. Difficulty: Hard.

From Quiz: The Maryland Blue Crab
 
Some incorrect choices:
The Gulf of Mexico, The Atlantic Ocean, The Delaware Bay

6. Can hermit crabs be bred in captivity?


Answer: Only with tide simulation

Interesting Information:
Hermit crabs are difficult to breed in captivity because they need natural ocean currents to be simulated, and plankton for the young to feed on. Difficulty: Hard.

From Quiz: The Hermit Crab
 
Some incorrect choices:
Only the white variety, Its not possible, Only in temperatures above 80'F

7. The robber crab is commonly believed to be the largest what in the world?


Answer: Arthropod that lives on land

Interesting Information:
The robber crab can reach over three feet in length and since arthropods have heavy exoskeletons, scientists believe it is impossible for an undiscovered arthropod to be bigger, as the exoskeleton would make it practically immobile. Robber crabs have been found to weigh up to nine pounds, but most are smaller. Difficulty: Hard.

From Quiz: The Selfish Shellfish
 
Some incorrect choices:
Crab species, Swimming crustacean, Shellfish

8. The scientific name for the common (or green) shore crab is what?


Answer: Carcinus maenas

Interesting Information:
The other three scientific names belong to other crustaceans. Cancer pagurus is the edible crab. It is very common and has a very recognisable 'pie-crust' style shell. Pagurus bernhardus is the common hermit crab. The hermit crab commonly occupies winkle and whelk shells, and once it gets too large for the shell, it will seek out a larger one. Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
Cancer pagurus, Pagurus bernhardus, Necora puber

9. Daphnia are usually seen in large crowds, but how do they reproduce so successfully?


Answer: Sexually and asexually

Interesting Information:
Daphnia usually breed through parthenogenesis, where a female produces live young solely from her own genes but not genetically identical. For the winter period or times of drought males are used for normal sexual reproduction, where eggs are laid that can survive the winter period and hatch when the environment becomes less hostile. Males can only be created through sexual reproduction. Difficulty: Hard.

From Quiz: Daphnia Details
 
Some incorrect choices:
Sexually, Asexually, Cloning

10. The Latin name for the blue crab is "Callinectes sapidus", which means what?


Answer: "Beautiful swimmer that is savory"

Interesting Information:
Savory, absolutely. But beautiful is a stretch. Difficulty: Hard.

From Quiz: The Maryland Blue Crab
 
Some incorrect choices:
"Fierce bottom-dweller", "Swimming crustacean that is peevish", "Hard-shelled scavenger"

11. What is the proper way to hold a hermit crab?


Answer: On a flat palm

Interesting Information:
While hermit crabs can pinch, it is difficult for them to grab hold of flesh on a flat palm. Beware, they can scuttle very fast and fall! Difficulty: Hard.

From Quiz: The Hermit Crab
 
Some incorrect choices:
By the back of its shell, By its large pincer, Using a tool

12. The International Union for Conservation of Nature labels the robber crabs' conservation status as "data deficient." What specifically does this mean?


Answer: There is not enough information to properly label robber crabs

Interesting Information:
The International Union for Conservation of Nature states the data deficient is "is not a threatened category, although it indicates a need to obtain more information on a taxon to determine the appropriate listing." Usually the term is applied to newly discovered species or when a species is discovered in a new place and warrants reassessment of its conservation status. It had previously been considered vulnerable until 1996. Difficulty: Hard.

From Quiz: The Selfish Shellfish
 
Some incorrect choices:
The conservation status of robber crabs has never been studied, There are too few robber crabs in the wild to come to a correct conclusion, Robber crabs are in no danger whatsoever of becoming extinct

13. What is the largest crab on earth?


Answer: Japanese spider crab

Interesting Information:
Weighing up to 42 pounds, this is one big crab! Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
Snow crab, Brown crab, Alaskan king crab

14. What happens when lobsters 'molt'?


Answer: They grow a new shell

Interesting Information:
There are different groups of crustaceans that are officially classed as lobsters, but people usually mean the family of clawed lobsters when they say simply 'lobster'. Lobsters continue to grow in size for as long they live, which many experts believe could be indefinitely, if they are not captured, attacked in the wild or become diseased. As lobsters grow, they molt; they discard their old shell, eat it, and grow a new one. Difficulty: Very Easy.

From Quiz: Friendly Crustaceans Under the Sea
 
Some incorrect choices:
They migrate to cleaner water, They have babies, They die

15. The decorator crab has alternating colored bands on its legs. What color are these bands?


Answer: Black and white

Interesting Information:
The alternate black and white bands on its legs distinguish the decorator crab from other, similar species. Difficulty: Hard.

From Quiz: The Decorator Crab
 
Some incorrect choices:
Red and white, Blue and white, Yellow and red

16. A hermit crab out of its shell most resembles what?


Answer: A lobster

Interesting Information:
A hermit crab looks very much like a small lobster, except their tails are curved to hold the inside of their "borrowed" shell, and are not covered by shell (fleshy). Difficulty: Hard.

From Quiz: The Hermit Crab
 
Some incorrect choices:
A spider, A snail, A seahorse

17. What is the largest land living arthropod in the world?


Answer: Coconut crab

Interesting Information:
They use "branchiostegal lungs" instead of vestigial gills. Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
Trilobites, Scorpions, Jumbo shrimp

18. Velvet swimmer crabs are very distinctive crabs. They are found under rocks and in small pools on the shore. Their rearmost legs are flattened so they can swim better (hence the name). When they are adults, what colour are their eyes?


Answer: Red

Interesting Information:
They have piercing red eyes, and should hopefully put you off touching them! They are very aggressive crabs, and will not hesitate to nip you with their powerful claws. Juveniles tend to have black eyes, and gradually as they grow up, their eyes turn red. Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
Black, Yellow, Grey

19. The decorator crab is known for its habit of adorning itself with bits of seaweed, hydroids, sponges and other intertidal debris. How is this accomplished?


Answer: Using a glue-like substance that is secreted from the mouth

Interesting Information:
The camouflage is placed on hook shaped hairs on the carapace using a glue-like substance that is secreted through the crab's mouth. Difficulty: Hard.

From Quiz: The Decorator Crab
 
Some incorrect choices:
Using the oils from fish, Using an oily substance produced from the crabs tear ducts, By turning ocean sand into a sticky glue-like substance

20. What gives daphnia their common name 'water fleas'?


Answer: The way they swim

Interesting Information:
While some daphnia are shaped roughly like fleas, and distantly related to all insects, they certainly do not bite or suck blood as parasites. The reason they are called fleas is the way they appear to jump through the water in sudden jerks. Difficulty: Hard.

From Quiz: Daphnia Details
 
Some incorrect choices:
They are directly related to fleas, They bite other animals, They look like fleas

21. How big was the largest recorded blue crab from Maryland from tip to tip of its shell?


Answer: Nine inches

Interesting Information:
Larger crabs, measuring ten to eleven inches, have been seen by survey performers. Difficulty: Hard.

From Quiz: The Maryland Blue Crab
 
Some incorrect choices:
Three feet, Six inches, Two feet

22. A hermit crab in the wild feeds on...


Answer: All of these

Interesting Information:
Wild hermit crabs have a huge variety of things they will eat. Some other things include worms and fish eggs. Difficulty: Easy.

From Quiz: The Hermit Crab
 
Some incorrect choices:
Leaves and foliage, Decaying meat, Plankton

23. Which Swedish scientist named the species Cancer latro, Latin for robber crab?


Answer: Carl Linnaeus

Interesting Information:
Carl Linnaeus is known as the father of taxonomy, taxonomy being the way animals are classified and grouped together. Linnaeus was not the first to name the species, but his scientific classification (renamed as Burgis latro) is the one used in present times. Previously, the species had been Cancer crumenatus. Difficulty: Hard.

From Quiz: The Selfish Shellfish
 
Some incorrect choices:
Charles Darwin, Gregor Mendel, Tycho Brahe

24. What is the primary material that composes the exoskeletons of a crab?


Answer: Calcium carbonate

Interesting Information:
It is one of the half dozen or so cell salts that also compose the human bones. It is used in homeopathy as a base for the formulas which have been popular since the turn of the last century. Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
Silica, Astaxanthin, Bone

25. The decorator crab can be found in what type of habitat?


Answer: Usually among seaweed in intertidal zones, and in subtidal waters

Interesting Information:
The decorator crab can be found in subtidal waters up to a depth of 1,439 feet. Difficulty: Hard.

From Quiz: The Decorator Crab
 
Some incorrect choices:
Among coral reefs, In freshwater lakes and streams, Usually in or around schools of fish

26. Which appendages do daphnia primarily use for swimming?


Answer: Second antennae

Interesting Information:
The cause of the jumping movement while swimming is the large second antennae which are used to propel the daphnia through water. It could be compared with the butterfly stroke which has similar effects. Difficulty: Hard.

From Quiz: Daphnia Details
 
Some incorrect choices:
First antennae, Front legs, Rear legs

27. What does it mean if there is a pink dot on the back fin of a crab?


Answer: The crab will molt in about a week.

Interesting Information:
The pink dot is actually the new shell appearing under the old. Within a week the crab will molt and shed its shell. The crab does this several times in its lifespan as it grows. Difficulty: Hard.

From Quiz: The Maryland Blue Crab
 
Some incorrect choices:
The crab has mated and is ready to spawn., The crab is marked by surveyors and should not be harvested., The crab is not a blue crab, but an Asian relative being introduced into the Chesapeake Bay.

28. In which scientific subphylum do hermit crabs belong?


Answer: Crustacea

Interesting Information:
While many people think hermit crabs look like spiders, they actually have very few similarities. Difficulty: Average.

From Quiz: The Hermit Crab
 
Some incorrect choices:
Arachnida, Amorphic, Nocturnal

29. Why is it recommended that one should NOT eat robber crab while vacationing in the South Pacific, where it sometimes appears on menus?


Answer: Robber crabs may be poisonous

Interesting Information:
While robber crabs are not normally poisonous, they can be if they ate fruit that is toxic to humans. Native people from various South Pacific islands consume the robber crab on occasion, but it is not a major part of any culture's diet. Difficulty: Hard.

From Quiz: The Selfish Shellfish
 
Some incorrect choices:
Robber crabs eat poisonous spiders, Humans cannot digest robber crabs, Robber crabs taste like sour milk

30. Hermit crabs belong to the superfamily Paguroidea. Most carry their gastropod shell around with them. Roughly how many species are known?


Answer: 1100

Interesting Information:
Most species have spiral shaped abdomens. Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
100, 500, 10,000

31. Officially, how many 'feet' do clawed lobsters have?


Answer: 10

Interesting Information:
Clawed lobsters belong to the order of decapods, meaning ten feet. When just looking at a lobster, you might think you count only eight feet. This is because their front legs have evolved into the claws, but they are still considered feet and not hands. Difficulty: Hard.

From Quiz: Friendly Crustaceans Under the Sea
 
Some incorrect choices:
8, 2, 12

32. Another popular name the decorator crab goes by is?


Answer: Graceful decorator crab

Interesting Information:
The decorator crab is also known as the graceful decorator crab due to its graceful nature and surprising ability to use its surroundings to blend in. Difficulty: Hard.

From Quiz: The Decorator Crab
 
Some incorrect choices:
Sponge crab, Oval spider crab, Rough shore crab

33. What is the main function of daphnia's legs?


Answer: Feeding

Interesting Information:
The main purpose of the legs is to direct the current into their digestive tract, feeding on most unicellular material that comes in. The front two pairs of legs also act as filters to keep larger material out. The swimming is mainly carried out by the antennae. Difficulty: Hard.

From Quiz: Daphnia Details
 
Some incorrect choices:
Swimming, Walking when out of water, They are vestigial with little function

34. What is the pincer sometimes called?


Answer: Cheliped

Interesting Information:
The two front claws are not used for locomotion. The larger is used for defense while the smaller is used to bring food to the mouth. Difficulty: Hard.

From Quiz: The Hermit Crab
 
Some incorrect choices:
Killepod, Defense Claw, "The finger"

35. How do the antennae of robber crabs compare to those of other crab species?


Answer: Robber crabs' are much shorter

Interesting Information:
In general, crabs have long antennae because they live in water and need the extra length to smell food in water. Robber crabs, however, live on land and do not need the length. The sense of smell is one of the robber crabs' most developed, but it has a fairly small and undeveloped brain. Scientists compare the antennae of the robber crabs to those of insects. Difficulty: Hard.

From Quiz: The Selfish Shellfish
 
Some incorrect choices:
Robber crabs do not have antennae, Robbert crabs' are much longer, All species of crabs have about the same size antennae

36. What is another name for the 'langostino' lobster?


Answer: Squat lobster

Interesting Information:
There are about 900 known species known. Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
Maine lobster, Crawdad, Rock prawn

37. Including the pincers, how many legs do hermit crabs have?


Answer: 10

Interesting Information:
The hind 2 pairs of a hermit crab's legs are usually inside the shell, used for grasping the borrowed shell. Difficulty: Hard.

From Quiz: The Hermit Crab
 
Some incorrect choices:
8, 6, 12

38. What, since 2005, has been endangering the once well-protected robber crabs on Christmas Island, an Australian territory in the Indian Ocean?


Answer: Construction and development projects

Interesting Information:
Robber crabs on Christmas Island are genetically different from other robber crabs. Australia had protected the crabs on the island until around 2001 when the government started using the island as a temporary immigration detention center. When a permanent complex was built in 2005, the robber crabs started being crushed by vehicles and experienced loss of habitat. Between January 2010 and November 2014, over 3,400 robber crabs had been killed on the island by traffic directly related to the immigration center, according to Max Orchard, an conservation activist. Difficulty: Hard.

From Quiz: The Selfish Shellfish
 
Some incorrect choices:
An influx of sea serpents, Bullfrogs over running the island, Active nuclear missiles struck the island

39. What antioxidant is responsible for the red coloring of crabs and lobster?


Answer: Astaxanthin

Interesting Information:
Much more powerful than other carotenes, astaxanthin in commonly marketed in stores and featured on shows like "Dr. Oz". Difficulty: Hard.

From Quiz: All About Crabs!
 
Some incorrect choices:
Red #5, Beta carotene, Vitamin A

40. Biologically, how can you tell a shrimp from a prawn?


Answer: Both of these

Interesting Information:
Shrimp have lamellar gills (meaning thin and plate-like), whereas prawns have branching gills. The simplest way to visually distinguish a shrimp from a prawn, though, is by looking at the second abdominal segment. In shrimps, the second segment overlaps both the first and third segments. The second abdominal segment of a prawn overlaps only the third segment. Difficulty: Hard.

From Quiz: Friendly Crustaceans Under the Sea
 
Some incorrect choices:
The gill structure, The abdominal segment, Neither of these
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