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What’s the difference between snakes and legless lizards? Specimen of the Week 248

By Jack Ashby, on 15 July 2016

Sloworms are legless lizards. LDUCZ-X206

Slow worms are legless lizards. LDUCZ-X206

Slow worms – They don’t have a leg to stand on

Not all legless reptiles are snakes, like this slow worm which is just one of the many kinds of legless lizards. The complete or near loss of limbs has evolved in lizards a great number of times. Some entire lizard families are legless. Some families contain a few species with tiny vestigial limbs, while the rest are limbless. Some families are mostly “normal” four-limbed species, with limblessness, near limblessness, or two-leggedness having evolved in certain lineages independently. The biggest lizard family – the skinks (of which there are 1500 of mostly leggy species) – has groups that have lost their limbs on numerous occassions in Africa, Europe and Australia. In most cases of legless lizards, some remnant of the hindlimbs is visible, often by the precence of scaly flaps.

Getting legless

Leglessness evolves when the legs become a hindrance rather than a help in an animals’ locomotion, and in lizards this is normally to do with burrowing. Essentially lizards have found that it is more effective to “swim” through the soil, pushing their way through little gaps with their heads. If you think about it, this makes sense because lizards’ arms aren’t that close to their snouts, so using them to dig can be a it awkward. This is one also one of the main hypotheses for how and why snakes evolved. Swimming is also a driving factor for losing limbs.

How do you tell a snake from a legless lizard?*

(more…)

Bits of animals that are surprisingly the same size – Vol. 1

By Jack Ashby, on 2 March 2016

The other day, two skulls were next to each other on the trolley – a capybara and a hyena. One is the world’s largest rodent, from the wetlands of South America, the other is a large carnivore from Sub-Saharan Africa, and as such are not often found together in museums.

Capybara and spotted hyena skulls, which are surprisingly the same size. (LDUCZ-Z180 and LDUCZ-Z2589)

Capybara and spotted hyena skulls, which are surprisingly the same size. (LDUCZ-Z180 and LDUCZ-Z2589)

I was amazed that they were the same size. This inspired me to find other bits of animals that are surprisingly the same size… (more…)

What’s the difference between seals and sea lions?

By Jack Ashby, on 26 December 2013

This is one of the easier spots in our “What’s the difference” series, but also one of the most commonly erred of all the picked nits. Zoologists are a pedantic bunch, and whilst correcting people just to demonstrate that you know more than them is not an effective engagement model, the world would be a better place* if more people landed on the right side of the seal vs sea lion dichotomy. The difference is, after all, at the same taxonomic level as otters and red pandas, and few would confuse them.

Seals vs Sea lions: The taxonomy of seal-ish things

All of these things are pinnipeds – a sub-group of the order Carnivora. Pinnipeds are split into three families – True Seals (Phocidae); Eared Seals (Otariidae) and the Walrus (the sole member of Odobenidae).
Let’s dispatch with walruses – they are easy to spot with their tusks.

True seals cannot raise their bodies onto their hind or fore limbs

True seals cannot raise their bodies onto their hind or fore limbs

True seals are the animals that look most like overweight tubes of toothpaste – all of the species we get around the UK are true seals (except for the occasional walrus). Grey seals, leopard seals, elephant seals, harp seals and ringed seals are among the 19 species of true seals.
Eared seals are the 16 species that are commonly named sea lions – because of the males’ manes- and fur seals – because of their dense underfur (for which they were heavily persecuted).
Only true seals are “seals”. Eared seals are not seals; they just look a lot like them.

The two easiest characteristics to look out for when trying to work out whether an animal is a true seal or an eared seal (I expect you can guess what one of them is) are…
Q: Can it walk? (more…)

What’s the difference between a crocodile and an alligator?

By Jack Ashby, on 24 October 2013

Crocodiles and alligators are big nasty predators. All of them. (Except the ones that are small lovely predators). If you see one swimming towards you then be concerned. Whilst considering your impending doom, you may wish to ascertain the correct taxonomic position of the beast. Here’s a quick guide to help you tell the difference between crocs and gators…

An Australian freshwater crocodile. One of the smaller lovelier ones (a baby) (C) Jack Ashby

An Australian freshwater crocodile. One of the smaller lovelier ones (a baby) (C) Jack Ashby

Before that, I should explain that there are 23 members of the order Crocodylia, which contains both the crocodile family (Crocodylidae) and the alligator family (Alligatoridae), as well as the gharial (the sole member of the family Gavialidae). When I say “crocodile” I am referring to members of Crocodylidae, not all members of Crocodylia, otherwise there wouldn’t be much point to this post.

Things to ask to work out whether you are being eaten by a crocodile or an alligator… (more…)

Horn vs Antler

By Jack Ashby, on 11 July 2013

Bone of contention - is this horn or is this antler? It's horn.

Bone of contention – is this horn or is this antler?
Erm… It’s horn.

There are a few things that get certain zoologists wound up. I’m not talking about extinction and Jeremy Clarkson, I’m talking about relatively meaningless* distinctions that we like to pick up on when people land on the wrong side of  an invisible dichotomy. You can get blood boiling by referring to sabre-toothed “tigers” rather than “cats”; failing to say “non-avian” when referring to extinction of dinosaurs; or describing apes as monkeys (actually that’s technically true as apes evolved from monkeys and the rules of taxonomy therefore require apes to be monkeys). Among such picked-nits is the difference between horns and antlers. If only more people would remember this then fewer zoologists would die prematurely of high blood pressure… (more…)

Bear or Bare?

By Jack Ashby, on 18 June 2013

Whilst working on some new displays recently I stuck up a sign saying “Please bear with us whilst we develop new displays”. Some people thought this was a deliberate clever pun as the display included some bears and they believed the correct spelling to be “bare”. It seems that this is a common problem as the question “Bear or Bare” gets over 75 million results on Google. This may help you remember when to use “bear” and when to use “bare”.

1) If you are talking about the large mammal, say “bear”.

2) The adjective meaning naked is “bare”.

3) The verb meaning to carry or hold is “bear”. For example:

Bear in Mind  That's a bear's brain, by the way. And the skeleton's a bear too

Bear in Mind
That’s a bear’s brain, by the way. And the skeleton’s a bear too

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Starfish or Sea Star?

By Mark Carnall, on 10 June 2011

Last week a visitor asked whether starfish should be called starfish or sea stars. At the Grant Museum our asteroideans are labeled as starfish. Apparently, the confusing name is causing children and adults to identify starfish as fish rather than as echinoderms. Every now and then we get similar enquiries from visitors and students that arise when scientific pedantry meets commonly used names. For another example see our colleague from the Horniman Museum, Paolo Viscardi, clarify for once and for all that Apes are Monkeys, so deal with it.

A label from the Grant Museum that says that flying lemures are not lemurs and cannot fly
(more…)