science

Vertebrate

Vertebrate is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Vertebrate rather than just read about it. In short: Vertebrates (), also called craniates, are animals with a vertebral column and a cranium. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain.

Key takeaways

Vertebrate belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Vertebrate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Vertebrate from memory before moving on to harder problems.

Reference excerpt

Vertebrates (), also called craniates, are animals with a vertebral column and a cranium. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebrata ( VUR-tə-BRAY-tə) with some 65,000 species, by far the largest ranked grouping in the phylum Chordata. The vertebrates include mammals, birds, amphibians, and various classes of fish and reptiles. The fish include the jawless Agnatha, and the jawed Gnathostomata. The jawed fish include both the cartilaginous fish and the bony fish. Bony fish include the lobe-finned fish, which gave rise to the tetrapods, the animals with four limbs. Despite their success, vertebrates still only make up less than five percent of all described animal species. The first vertebrates appeared in the Cambrian explosion some 518 million years ago. Jawed vertebrates evolved in the Ordovician or Silurian; bony fishes appeared in the Silurian and diversified widely in the Devonian. The first tetrapods appeared towards the end of the Devonian, and the first amphibians appeared on land in the Carboniferous. During the Triassic, mammals and dinosaurs appeared, the latter giving rise to birds in the Jurassic. Extant species are roughly equally divided between fishes of all kinds, and tetrapods. Populations of many species have been in steep decline since 1970 because of land-use change, overexploitation of natural resources, climate change, pollution and the impact of invasive species.

Characteristics

Unique features Vertebrates belong to Chordata, a phylum characterised by five synapomorphies (unique characteristics): namely a notochord, a hollow nerve cord along the back, a post-anal tail, an endostyle (present in vertebrates as the thyroid gland), and pharyngeal gills arranged in pairs. Vertebrates share these characteristics with other chordates. Vertebrates are distinguished from all other animals, including other chordates, by multiple synapomorphies, namely: a vertebral column and a skull made of cartilage or bone; a brain divided into 3 or more sections; a muscular heart with 2 or more chambers; an inner ear with semicircular canals; camera-type eyes; a nose; kidneys with glomeruli; a thyroid; and a liver.

Physical

Vertebrates (and other chordates) belong to the Bilateria, a group of animals with mirror symmetrical bodies. They move, typically by swimming, using muscles along the back, supported by a strong but flexible skeletal structure, the spine or vertebral column. The name 'vertebrate' derives from the Latin vertebratus, 'jointed', from vertebra, 'joint', in turn from Latin vertere, 'to turn'.

As embryos, vertebrates still have a notochord. In all but the jawless fishes, it is replaced with a vertebral column (made of bone or cartilage) during development. Vertebrate embryos have pharyngeal arches; in adult fish, these support the gills, while in adult tetrapods they develop into other structures. In the embryo, a layer of cells along the back folds and fuses into a hollow neural tube. This develops into the spinal cord, and at its front end, the brain. The brain receives information about the world through nerves which carry signals from sense organs in the skin and body. Because the ancestors of vertebrates usually moved forwards, the front of the body encountered stimuli before the rest of the body, favouring cephalisation, the evolution of a head containing sense organs and a brain to process the sensory information. Vertebrates have a tubular gut that extends from the mouth to the anus. The vertebral column typically continues beyond the anus to form an elongated tail.

The ancestral vertebrates, and most extant species, are aquatic and carry out gas exchange in their gills. The gills are finely-branched structures which bring the blood close to the water. They are positioned just behind the head, supported by cartilaginous or bony branchial arches. In jawed vertebrates, the first gill arch pair evolved into the jaws. In amphibians and some primitive bony fishes, the larvae have external gills, branching off from the gill arches. Oxygen is carried from the gills to the body in the blood, and carbon dioxide is returned to the gills, in a closed circulatory system driven by a chambered heart. The tetrapods have lost the gills of their fish ancestors; they have adapted the swim bladder (that fish use for buoyancy) into lungs to breathe air, and the circulatory system is adapted accordingly. At the same time, they adapted the bony fins of the lobe-finned fishes into two pairs of walking legs, carrying the weight of the body via the shoulder and pelvic girdles. Vertebrates vary in size from the smallest frog species such as Brachycephalus pulex, with a minimum adult snout–vent length of 6.45 millimetres (0.254 in) to the blue whale, at up to 33 m (108 ft) and weighing some 150 tonnes.

Molecular Molecular markers known as conserved signature indels in protein sequences have been identified and provide distinguishing criteria for the vertebrate subphylum. Five molecular markers are exclusively shared by all vertebrates and reliably distinguish them from all other animals; these include protein synthesis elongation factor-2, eukaryotic translation initiation factor 3, adenosine kinase and a protein related to ubiquitin carboxyl-terminal hydrolase). A specific relationship between vertebrates and tunicates is supported by two molecular markers, the proteins Rrp44 (associated with the exosome complex) and serine C-palmitoyltransferase. These are exclusively shared by species from these two subphyla, but not by cephalochordates.

Evolutionary history

Cambrian explosion

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Vertebrate

Start with the simplest possible case. Write down what Vertebrate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Vertebrate before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Vertebrate ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Vertebrate

In research: Vertebrate appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Vertebrate in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Vertebrate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Extant Cambrian first appearances, Terreneuvian first appearances, Vertebrates, so understanding it makes those chapters shorter.
In everyday life: Look for Vertebrate outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Vertebrate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Vertebrate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Vertebrate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Vertebrate in simple terms?

Vertebrates (), also called craniates, are animals with a vertebral column and a cranium. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain.

Why does Vertebrate matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Vertebrate?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Vertebrate.