# Invertebrates with bones? **URL:** \ **Category:** Factual Questions\ **Created:** [August 30, 2007, 10:51pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547 "2007-08-30T22:51:59Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Muad\_Dib](https://avatars.discourse-cdn.com/v4/letter/m/35a633/32.png) [@Muad\_Dib](https://boards.straightdope.com/u/Muad_Dib)\ **Post date:** [August 30, 2007, 10:51pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/1 "2007-08-30T22:51:59Z")
Are there any? I could not think of any. ---
**Author:** ![Captain\_Carrot](https://avatars.discourse-cdn.com/v4/letter/c/f0a364/32.png) [@Captain\_Carrot](https://boards.straightdope.com/u/Captain_Carrot)\ **Post date:** [August 30, 2007, 10:54pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/2 "2007-08-30T22:54:27Z")
Um, doesn’t that kind of contradict the meaning of the word? How can you have bones without having a skeleton? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 30, 2007, 11:07pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/3 "2007-08-30T23:07:05Z")
Some arthropods have internal supporting skeletal structures - that is to say, it’s not _just_ an exoskeleton they have. ---
**Author:** ![Muad\_Dib](https://avatars.discourse-cdn.com/v4/letter/m/35a633/32.png) [@Muad\_Dib](https://boards.straightdope.com/u/Muad_Dib)\ **Post date:** [August 30, 2007, 11:11pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/4 "2007-08-30T23:11:08Z")
[QUOTE=Captain Carrot] Um, doesn’t that kind of contradict the meaning of the word? How can you have bones without having a skeleton? [/QUOTE] Invertebrate means it is without a spine, not an entire skeleton. ---
**Author:** ![andros](https://avatars.discourse-cdn.com/v4/letter/a/e480ec/32.png) [@andros](https://boards.straightdope.com/u/andros)\ **Post date:** [August 30, 2007, 11:18pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/5 "2007-08-30T23:18:20Z")
[QUOTE=Captain Carrot] Um, doesn’t that kind of contradict the meaning of the word? How can you have bones without having a skeleton? [/QUOTE] Well, invertebrates (every animal species not _Chordata_) by definition have no spinal column, which wouldn’t _necessarily_ preclude them from having other bones . . . but in practical terms, you’re spot-on. AFAIK, the only other phylum that comes close is _Echinoderma_–sea stars, cukes, and urchins. Their plates and spines are ossified, and probably as close to proper bone as an invertebrate will get. . ---
**Author:** ![andros](https://avatars.discourse-cdn.com/v4/letter/a/e480ec/32.png) [@andros](https://boards.straightdope.com/u/andros)\ **Post date:** [August 30, 2007, 11:21pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/6 "2007-08-30T23:21:20Z")
[QUOTE=Muad’Dib] Invertebrate means it is without a spine, not an entire skeleton. [/QUOTE] Wellnow, do you want to know about _bones_ or _skeletons_? There are plenty of critters with exoskeletons, of course, some with hydroskeletons, and some running the Hybrid Synergy Skeleton (cuttlefish come to mind). . ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 30, 2007, 11:33pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/7 "2007-08-30T23:33:52Z")
The [Giant Pacific Gumboot Chiton](http://www.coastalwebweaver.com/GumbootChiton/index.html) has eight butterfly shaped skeletal plates, which are kind of _like_ bones. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [August 30, 2007, 11:38pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/8 "2007-08-30T23:38:24Z")
_Cuttlefish_ (a relative of the squid) have cuttlebone. wiki: _Cuttlefish possess an internal structure called the cuttlebone, which is composed of calcium carbonate and is porous, to provide the cuttlefish with buoyancy. Buoyancy can be regulated by changing the gas-to-liquid ratio in the chambered cuttlebone. Each species has a distinct shape, size, and pattern of ridges or texture on the “bone”. Cuttlebones are traditionally used by jewelers and silversmiths as moulds for casting small objects. They are probably better known today as the tough material given to parakeets and other cage birds as a source of dietary calcium. The cuttlebone is unique to cuttlefish, one of the features contrasting them with their squid relatives._ ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [August 30, 2007, 11:49pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/9 "2007-08-30T23:49:28Z")
“Bone” is defined to be what vertebrates have, but if you mean bone-like structure, then I think the question has been answered. For it to be a “bone”, though, it has to be in a vertebrate. ---
**Author:** ![andros](https://avatars.discourse-cdn.com/v4/letter/a/e480ec/32.png) [@andros](https://boards.straightdope.com/u/andros)\ **Post date:** [August 31, 2007, 1:24am UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/10 "2007-08-31T01:24:58Z")
. FWIW, _in re_ the cuttlefish, I seem to recall that their “bone” derived from an absorbed exoskeleton. . ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [August 31, 2007, 3:04am UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/11 "2007-08-31T03:04:12Z")
[QUOTE=John Mace] “Bone” is defined to be what vertebrates have, but if you mean bone-like structure, then I think the question has been answered. For it to be a “bone”, though, it has to be in a vertebrate. [/QUOTE] Right. “Bone” refers to a specific kind of tissue, which only vertebrates have. The main mineral in bone is calcium phosphate. Vertebrates are nearly unique among animals in having a skeleton made of calcium phosphate. The hard shells of mollusks are made up of calcium carbonate, in the form of calcite or aragonite. This includes the so-called cuttlebone of cuttlefish, which is really just an internal shell. The hard parts of insects are made up of chitin. The exoskeleton of crustaceans is made up of chitin, often reinforced with calcium carbonate. ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [September 15, 2007, 11:24pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/12 "2007-09-15T23:24:17Z")
[QUOTE=andros] Well, invertebrates (every animal species not _Chordata_) by definition have no spinal column, which wouldn’t _necessarily_ preclude them from having other bones . . . but in practical terms, you’re spot-on. [/QUOTE] Actually, invertebrates are animals not in the subphylum _Vertebrata_. The phylum _Chordata_, which subsumes _Vertebrata_, consists of all animals which develop a notochord. In vertebrates, this notochord develops into a bony vertebral column. (There are other subphyla of _Chordata_ whose members develop neither vertebrae nor any other bones.) As it happens, there is one branch of chordates which develop bones but no vertebrae: the hagfish. They have bony skulls, but their notochord is never replaced with a vertebral column, making them literal invertebrates. The actual taxonomy of hagfishes is uncertain. Most biologists consider them to be degenerate vertebrates and place them in _Vertebrata_ even though they have no vertebrae. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [September 16, 2007, 11:21pm UTC](https://boards.straightdope.com/t/invertebrates-with-bones/417547/13 "2007-09-16T23:21:06Z")
[QUOTE=andros] . FWIW, _in re_ the cuttlefish, I seem to recall that their “bone” derived from an absorbed exoskeleton. . [/QUOTE] Not really an exoskeleton, just a shell as in the nautilus.