A Gallery of Crustaceans Trivia Quiz

Answer: Woodlouse

The woodlouse really is a curiosity with its ancient vibe and peculiar status as a crustacean that has successfully adapted to a fully terrestrial - rather than marine - existence. The pictured species is Oniscus asellus which is the common woodlouse, regularly seen across Britain and the west of Europe.

It has also spread to other countries around the world. The picture shows a favoured habitat of the common woodlouse, namely moist or rotting wood.

Answer: Barnacles

There are a wide variety of barnacles but two of the best known classifications are the goose barnacle and the acorn barnacle, the latter of which features in the image. The acorn barnacles - so named because of their shape - consist of a number of different species including the pictured Chthamalus stellatus or Poli's stellate barnacle that can be found in parts of the UK, Republic of Ireland and the south of Europe.

Poli's stellate barnacle is an example of a sessile barnacle, meaning it cannot move itself (that is, it lacks the innate ability of self-locomotion) but is instead moved by another force, in this case the tide. More often than not, barnacles will be seen firmly attached to a rock (or the underside of a boat or ship). Where there is a barnacle, there is a usually a limpet (a type of mollusc) nearby!

Answer: Lobster

The European lobster (also known simply as the common lobster) was originally given the taxonomic name of Cancer gammarus by Linnaeus in the 1750s. This wasn't because Linnaeus confused the lobster with the crab, rather it was his intention to place all large crustaceans into just one genus, Cancer.

The common lobster has since been reclassified a number of times but since the 1830s the species has been known as Homarus gammarus, sharing the Homarus genus with the American lobster (H. americanus).

Answer: False

Helix pomatia is also known as the Roman snail or escargot; as the latter of these indicate, this particular snail is edible and is used in the more adventurous reaches of French cuisine.

The Roman snail is not a crustacean, not least because it lacks jointed legs and a segmented body; it instead belongs to the molluscs, a phylum typified by a soft and unsegmented body (often acting as a muscular foot) that is protected by a shell. That said, molluscs such as slugs have evolved such that they no longer have a shell (or retain only a small vestigial shell) but are still categorised within the phylum all the same.

Answer: Clam shrimp

Branchiopod is derived from two Ancient Greek words that translate into "gill" and "foot". The branchiopod in the picture is a clam shrimp, a crustacean that has a varied diet but can broadly be classified as a detritivore as part of its diet consists of decaying matter.

The name clam shrimp derives from the two valves (bivalve) that make up the creature's clam-like shell. This shell is a crucial layer of defence but it is not used alone; the clam shrimp also plays dead in order to deter predators.

Answer: Devil crab

The velvet crab (Necora puber) is also called the devil crab because it sports a pair of protruding red eyes. This species has gone through a number of reclassifications over the centuries but has ultimately landed in a genus all of its own (Necora). Some of the reasons for the devil crab being separated from other ostensibly similar species relate to claw structure and the shell or carapace being velvety rather than smooth.

Answer: Krill

Krill is both abundant and ubiquitous (well, in the oceans at least) and this has to be the case in order to satisfy the nutritional needs of animals as large as baleen whales. In turn, this important crustacean feeds mainly on phytoplankton, such as cyanobacteria and a type of protist called the diatom.

Answer: Ghost crabs

The crab in the picture is the Atlantic ghost crab and it can most commonly be spotted along the East Coast of the USA (when they are not safely burrowed into the sand that is). Ghost crabs are known for their speed and this fact is reflected in the name of the subfamily of ghost crabs, Ocypodinae ("swift" and "foot").

The "ghost" description is due to the straightforward reason that they are a typically pale subfamily of crabs that are successfully camouflaged in white/yellow sands.

Answer: Vision

There are numerous species of mantis shrimp but this dazzling example is named after the peacock (for the obvious colour-related reason); this is far from its only name with alternatives starting with words such as harlequin, painted, clown and rainbow - take your pick!

Whatever you want to call it, Odontodactylus scyllarus is particularly noteworthy for its sight; it has a large number of different types of photoreceptors in its eyes, each of which convert light (of varying types of polarisation) to biologically useful signals in different ways. Their ability to visually process colour so effectively is helpful to them in their natural habitat, the coral reefs of the Indian and Pacific oceans.

Answer: Sally Lightfoot

Grapsus grapsus is known by a few names including the red rock crab (straightforward enough) and the Sally Lightfoot crab (how peculiar). According to the Galapagos Conservation Trust, the name is said to come from a Caribbean dancer and the species of crab shares her name "due to their agility in jumping from rock to rock, their ability to run in four directions and their capacity to climb up vertical slopes".

There are a number of other species within the Grapsus genus that also feature "lightfoot" (though in lower case) in the common name. It is also noteworthy that another species of crab (Percnon gibbesi) has the common name of Sally Lightfoot. Taxonomy is a messy business!