Big Book of Animals

Big Book of Animals — page 3 — Slugs and Snails Slugs and snails are a type of mollusk known as gastropods which means stomach foot after their single slimy suction-pad of a foot-muscle which they use to creep along There are about 75,000 species of gastropods now known on land and in the sea which makes them the largest class of mollusks Slugs and snails eat plants and are considered pests as they devour crops and flowers Their mouths are lined with rows of tiny teeth that wear down one after the other What is the largest land snail The biggest land-dwelling snail in the world is the giant African snail It can weigh more than 1 lb 9 oz 900g which is nearly as much as a bag of sugar Its body can reach 15 in 39 cm long and its shell alone can be as large as 10 in 27 cm long That’s bigger than a soccer ball It has been introduced from Africa into other warm countries as a pet in zoos or as a source of food In many of these countries it is now a pest as it has no natural predators Gastropods like the garden snail have a one-part shell so they are called univalves For farmers the giant land snail is South East Asia’s most destructive pest How does the garden snail survive in dry weather The garden snail survives dry spells by finding as dark and damp a place as it can and then retreating far into its shell to preserve moisture It leaves a layer of mucus around the edges of the outside that dries and sticks tight to the surface it is on It also seals off the outside with dried mucus leaving a door A snail’s shell provides plenty of protection Its vital organs are housed within it and the shell grows in a spiral as the snail grows Like all mollusk shells a snail’s shell is made from a tough substance called calcium carbonate

Big Book of Animals — page 4 — Why do slugs and snails leave a trail of slime Like all slugs and snails the great black slug needs moisture to survive It travels along the ground over a layer of slimy mucus It is this mucus that causes its trail To produce this mucus its body needs to have a higher than average water content The great black slug eats rotting vegetation and even the dead bodies of other slugs It has a breathing hole behind its head on the right-hand side and like other slugs and snails it uses tentacles that can touch and smell to find food Like other gastropods slugs lay eggs When they hatch baby slugs look like miniature adults 0.5 in 1.3 cm per second at top speed That’s fast for a snail How fast is a garden snail Sea slugs are found mainly in the Red Sea and Indian and western Pacific Ocean slugs differ from land slugs How do sea Sea slugs belong to a completely different order of animals to slugs called Nudibranchia Instead of having a pair of lungs like land slugs sea slugs breathe through gills arranged in clumps on their backs that look a bit like plants Like their land dwelling relatives they are slow moving and do not have shells They have a nasty poisonous taste and warn predators of this by being among the most brightly colored animals in the sea

Big Book of Animals — page 5 — Squid and Octopuses Squid cuttlefish and octopuses are specialized mollusks known as cephalopods They are the only invertebrates to have filled the same niche as fish Unlike most other mollusks octopuses and squid have no external shell Squid have an internal shell and have 10 suckered legs Octopuses have no shell at all and have 8 legs or tentacles Both have a beak-like mouth and highly developed senses with sophisticated eyes that are similar to those belonging to mammals How do reef squid move Like all cephalopods the reef squid moves using jet propulsion It sucks water in and jets it out again propelling itself in the opposite direction The Caribbean reef squid is often found in shallow reefs and is not scared of divers Their bodies are broad and less streamlined than many other squids so they aren’t quite as nimble They are a mottled green-brown on one side with lighter coloring on the other as camouflage Blue-ringed octopuses have two separate poison glands one to attack prey and the other for defense Are blue-ringed octopuses dangerous They are very dangerous They are the most deadly of all cephalopods to humans The greater blue-ringed octopus carries enough venom to kill 26 adult humans in minutes and it is only about the size of a golf ball This venom is more potent than any venom found in land animals Luckily they are not aggressive and will only sting in self-defense Large shining blue rings cover its surface and they light up when it is alarmed How brainy is an octopus Cephalopods have the largest brains of all the invertebrates and the common octopus has one of the largest brain-to-body size ratios making it the cleverest known invertebrate Scientists have conducted tests that prove its ability to learn complex signs to get food Its brainy behavior in the wild includes using its tentacles to search crevices and rocks to find crabs and other small animals It feeds by drawing food close with its suckered arms and biting its prey with its beak-like mouth Reef squid can communicate through changing the color of their skin

Big Book of Animals — page 6 — Does anything eat giant squid Giant squid and other deep sea squid are a significant part of a sperm whale’s diet Dramatic underwater battles take place and sperm whales may be permanently scarred by these encounters as the squid fights back and tries to escape The giant squid can reach lengths of up to 59 ft 18 m and can weigh up to 1 ton 900 kg They For how long does a blue-ringed octopus live don’t live long averaging just two years No one has seen a giant squid in its natural habitat as it lives at such great depths Common octopuses are usually solitary and defend their territories from others

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