As a noun, an individual is only one person or thing, not a group. An individual can also mean someone who is different from anyone else (one a kind).
Truck
A truck (or lorry in British English) is a motor vehicle used to transport goods. The word "truck" comes from the Greek word ""trochos"", which means "wheel". Most trucks use diesel fuel.
"Light trucks" are trucks the size of cars. They are used by individuals and also companies. In the United States, a truck is a light truck if it weighs less than 6,300 kg (13,000 lb). Light trucks are only a little heavier than vans or pickup trucks, but require a special driver's license.
"Medium trucks" are heavier than light trucks but lighter than heavy trucks. In the United States, a truck is a medium truck if it weighs between 6,300 kg (13,000 lb) and 15,000 kg (33,000 lb). Trucks that are used for local delivery and public service (dump trucks, garbage trucks) are normally around this size. Medium trucks have usually two axles: one at front and one at rear. The rear wheels may be coupled (that is: two wheels hitched together) to enable heavier load, but they may also be single.
"Heavy trucks" are the heaviest trucks that are allowed on the road. In the U.K. they are known as "lorries". Usually heavy trucks have three axles: one at front and two at rear, and the rear axles have coupled wheels to enable heavy loads. Often heavy trucks pull trailers. They can be either "full trailers" which have both front and rear axles or boggies and their own brakes, and are connected to the towing truck with a towbar, or "semi-trailers", which are attached to a special kind of a truck called "tractor unit" with a turntable coupling ("fifth wheel"). A semi-trailer is a kind of trailer which has wheels only in the back and the front rides on the back of the tractor unit. The tractor unit has an engine and the semi-trailer does not. Driving a heavy truck requires a professional driver's license. Truck drivers are called "truckers".
The laws of various countries say what kind of vehicle combinations are allowed. A semi-trailer can be converted into a full trailer with using a "dolly". A dolly is a small trailer which has only a bogie (= set of wheels), fifth wheel coupling for the semi-trailer and a towbar. Using a dolly, the semi-trailer can now be hitched to an ordinary cargo-carrying truck and does not need a tractor unit.
A heavy truck-trailer combination is often called big rig or eighteen-wheeler.
The largest heavy trucks are the Australian "road trains" which may have up to four semi-trailers coupled to a tractor in a train-like fashion and may carry up to 200 tonnes of cargo.
Box trucks or Dry vans ("tilts" in the UK) have walls and a roof, making a closed cargo room. The rear has doors. Some have a side door.
Concrete mixers have a turning drum on back. Turning it one way mixes the concrete. Turning it the other way pushes the concrete out. The concrete goes down "chutes" (like large pipes with an open top). On most trucks the concrete comes out the back. Some new types have the concrete goes over the cab and down chutes in the front. Concrete is very heavy and hard to mix. Concrete mixers have to be very heavy duty.
Dump trucks ("tippers" in the UK) carry sand, gravel, and dirt. Most dump trucks have an open-top box bed with an opening "tail-gate" door on the back. The body lifts up at the front. The load falls out the tailgate and is "dumped" on the ground behind the truck.
Flatbed trucks have a flat body with no sides. There is a wall between the cab and the body. The load will not move forward and hit the cab. The truck can be loaded from the side or top. Nothing covers the load. Some trucks have sides that can be taken off or folded down. Many times the load is covered with tarps.
Garbage trucks pick up garbage and trash from homes and some businesses. Most were loaded from the rear. Now some load from the front or side. The same type of truck is often used for recycling.
Semi-tractors ("artics" in the UK) have no bodies. They have a "fifth wheel" that carries weight. A semi-trailer has no front wheels. The front of the trailer goes on the fifth wheel. The semi-tractor carries weight from the trailer and pulls the trailer
Tank trucks ("tankers" in the UK) are designed to carry liquids or gases. They usually have a round tank that is long (a cylinder) lying on its side. There are many types of tanks because there are many liquids and gases. Most tankers are built for only one liquid.
Wreckers ("recovery lorries" in the UK and sometimes "tow trucks" in the US) are used to lift and tow broken cars and trucks. They usually have a boom with a cable. Cars are often carried on special flatbeds.
Crown-of-thorns starfish
The crown-of-thorns starfish ("Acanthaster planci") is a type of sea star. Usually, they have orange-red to purplish skin, with yellow or pink spikes on their skin. The crown-of-thorns is also one of the largest starfish in the world, as it has a diameter of up to 3 feet. The crown-of-thorns lives in the warmer areas of the Pacific Ocean, Indian Ocean, and Red Sea.
It only feeds on coral polyps, and usually at night. The crown-of-thorns climbs over its prey, releases digestive enzymes to break down its food, and then absorbs the coral polyp, which has now turned into a liquid. What's left behind by the sea star is the leftover coral skeleton.
They are usually of subdued colours, pale brown to grey-green, but they may be garish with bright warning colours in some parts of their wide range. These bright colours warn animals that may want to eat it that it is venomous.
The crown-of-thorns is well known for its destructive habits of eating coral, especially on the Great Barrier Reef, which is a World Heritage Site. Usually, when there are not too many of them, these sea stars help maintain the coral reef by preventing the faster-growing coral from taking over the coral reef. However, when there are too many crown-of-thorns, they can devastate the reef.
Sea urchin
Sea urchins are the Class Echinoidea of the Phylum Echinodermata. Like the rest of the Echinoderms, literally "spike-skinned", they are entirely marine. They are usually globe-shaped, and protected by calcareous plates and spines. "Urchin" is an old word for hedgehog, and in many foreign languages these animals are called "sea hedgehogs".
Like other echinoderms they have five-fold symmetry (called pentamerism) and move by means of hundreds of tiny, transparent, adhesive 'tube feet'. The symmetry is not obvious in the living animal, but is easily visible in the dried test.
Sea urchins mostly feed on algae and small animals. They have a special chewing apparatus called "Aristotle's lantern", after the Greek philosopher Aristotle who was fascinated by sea urchins. With this apparatus they can scrape organisms stuck to the surface over which the urchin is moving.
The spines are long and sharp in some species, and protect the urchin from predators. The spines inflict a painful wound when they penetrate human skin, but are usually not dangerous. Echinoids also have pincer-like pedicellaria all over their body between the spines. The job of these is to deal with anything (like larvae) settling on the test (outer shell). It is not known if the spines are venomous (unlike the pedicellariae between the spines, which are venomous).
Typical sea urchins have spines that are in length, thick, and not terribly sharp. "Diadema antillarum", familiar in the Caribbean, has thin, potentially dangerous spines that can reach long.
Sea urchins have five jaws with one tooth each. The teeth grow throughout the sea urchin's life. The teeth of the pink sea urchin chip against each other to stay sharp.