Incredible Invertebrates



9 Questions

What percentage of animal species are estimated to be invertebrates?

Which of the following is a paraphyletic group?

What is the largest group of described invertebrate species?

Which of the following is a common trait of all invertebrates?

Which of the following respiratory systems is found in terrestrial arthropods?

Which of the following is a field that invertebrates have benefited?

Which of the following model organisms is commonly studied by scientists?

Which of the following is a use of invertebrates by scientists in the field of aquatic biomonitoring?

What is the significance of the division of the Animal Kingdom into vertebrates and invertebrates according to the text?


Animals without a vertebral column:

  • Invertebrates are animals that do not possess or develop a vertebral column derived from the notochord, and include arthropods, mollusks, annelids, echinoderms, and cnidarians.

  • There are an estimated 97% of animal species that are invertebrates, which is a greater number and variety of species than the entire subphylum of Vertebrata.

  • Some so-called invertebrates such as Tunicata and Cephalochordata are more closely related to vertebrates than to other invertebrates, making the invertebrates a paraphyletic group.

  • The term invertebrates is not always precise among non-biologists since it does not accurately describe a taxon in the same way that Arthropoda, Vertebrata or Manidae do.

  • The largest number of described invertebrate species are insects, with over 95% of the described animal species in the world being invertebrates.

  • The trait common to all invertebrates is the absence of a vertebral column, and they require sustenance in the form of the consumption of other organisms.

  • Most multicellular organisms exhibit some form of symmetry, but some invertebrates, such as gastropods, have asymmetric body plans.

  • Invertebrates have neurons that differ from mammalian cells, but they are able to detect increasing pressures and tissue trauma.

  • Invertebrates have different respiratory systems, with terrestrial arthropods having an open respiratory system composed of spiracles, tracheae, and tracheoles.

  • Most invertebrates reproduce at least partly through sexual reproduction, with some capable of asexual reproduction as well.

  • Social behavior is widespread in invertebrates, including cockroaches, termites, aphids, thrips, ants, bees, Passalidae, Acari, spiders, and more.

  • Invertebrates can be classified into several main categories, some of which are taxonomically obsolescent or debatable but still used as terms of convenience.The Significance of Invertebrates: A Summary

  • Invertebrates are animals without a vertebral column and are classified into over 30 phyla.

  • The distinction of invertebrates and vertebrates persists to this day, even though the grouping has been noted to be "hardly natural or even very sharp."

  • Lamarck created a precedent through his classifications which is now difficult to escape from, leading to the continued distinction of invertebrates and vertebrates.

  • Invertebrate biology was not a major field of study until the work of Linnaeus and Lamarck in the 18th century.

  • During the 20th century, invertebrate zoology became one of the major fields of natural sciences, with prominent discoveries in the fields of medicine, genetics, palaeontology, and ecology.

  • Invertebrates have benefited law enforcement, as arthropods and insects were discovered to be a source of information for forensic investigators.

  • The fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans are two of the most commonly studied model organisms nowadays.

  • Invertebrates are also used by scientists in the field of aquatic biomonitoring to evaluate the effects of water pollution and climate change.

  • Analysis of the starlet sea anemone genome has emphasized the importance of sponges, placozoans, and choanoflagellates, also being sequenced, in explaining the arrival of 1500 ancestral genes unique to animals.

  • Invertebrates are a diverse group that lumps a vast number of species together, so that no one characteristic describes all invertebrates.

  • Some species included are only remotely related to one another, with some more related to vertebrates than other invertebrates.

  • The division of the Animal Kingdom into vertebrates and invertebrates is artificial and reflects human bias in favor of man's own relatives.


Test your knowledge about animals without a vertebral column with this quiz! From arthropods to cnidarians, invertebrates are a diverse group of animals that make up an estimated 97% of all animal species. See how much you know about their characteristics, behaviors, and significance in the field of biology. This quiz will challenge your understanding of invertebrates and their importance in the natural world.

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