Examples of Invertebrates: Definition, Characteristics & Classification

Examples of Invertebrates – Broadly speaking, the kingdom animalia can be grouped into two groups, namely the class of vertebrates (animals with backbones) and the group of invertebrates (animals without backbones). The following will explain the characteristics, body layer structure, and classification of the kingdom Animalia Invertebrata Sinaumed’s!


Invertebrates are animals that do not have a backbone or vertebral column. Most of the animals are invertebrates. The term Invertebrata itself is an early form of ‘Vertebra’ which comes from the Latin word. ‘Vertebra’ generally means joint, the specific meaning is ‘vertebral joints of the spine’. This word is added with the prefix “in” meaning not or without, which means ‘those who are not veterbrae’.

Porifera Invertebrates or Invertebrates is a term expressed by Chevalier de Lamarck to designate animals that do not have a backbone. Invertebrates include almost all animals except vertebrates (reptiles, birds, fish, amphibians, and mammals). Invertebrates are the most diverse group and have about 12 million living species. Most of the animals on earth are invertebrates. They are cold-blooded animals with a body temperature that depends on the temperature of the atmosphere.

In learning more about invertebrates, Sinaumed’s can read the book Invertebrate Zoology (Theory and Practice) by Adun Rusyana which provides all information about invertebrates.


The main feature that separates invertebrates from other organisms is the absence of a spine and backbone. They are multicellular organisms, they really don’t have a cell wall:

  • Animali Invertebrates do not have a hard endoskeleton due to the lack of a complex bone system, some invertebrates tend to be slow and small in nature. Due to the lack of a backbone and a complex nervous system, invertebrates cannot inhabit some environments, although they are found in harsh environments.
  • Invertebrates’ bodies are divided into three parts – head, thorax and abdomen. They do not have lungs for respiration. Respiration occurs through the skin. Several groups of invertebrates have a hard exoskeleton of chitin. Most of them are networked, with a certain cell organization. Most also reproduce sexually by the fusion of male and female gametes. Some invertebrates such as sponges are sedentary, but most organisms are motile. Most invertebrates are arranged with a symmetrical body organization. They are unable to make their own food or
  • Invertebrates are the most diverse organisms present on earth. Almost 95% of the animal population from invertebrates. According to the International Union for Conservation of Nature in 2009, more than 1.3 million invertebrates were identified. Invertebrates make up about 75% of the known species on the Planet. The actual number of invertebrates is unknown, there are some predictions that there may be tens of millions of invertebrates, mostly insects. Invetebrata includes all animals that do not belong to the phylum Chordata. Common examples include clams, slugs, spiders, cockroaches, worms, star fish, octopus, the following are some of the Sinaumed’s class of Animalia invertebrates:
  • Porifera – Sponges, Sycon (scypha), Spongilla (freshwater sponges) and Euspongia (bath sponges).
  • Cnidaria – Aurelia, Adamis, Hydra, sea anemone, Physalia (Portuguese warship), Pennatula, Gorgonia, Meandrina.
  • Ctenophora – Pleurobranchia and Ctenophora.
  • Platyhelminthes – Taenia (tapeworm), Fasciola (liver worm).
  • Aschelminthes – Ascaris (round worm), Wuchereria (filaria worm), Ancylostoma (hookworm).
  • Annelida – Nereis, Pheretima (earthworms) and Hirudinaria (bloodsucking leeches).
  • Arthropods – Apis (honey bee), Bombyx (caterpillar), Laccifer (lac insect); Mosquitoes – Anopheles, Culex and Aedes; Locusta (grasshopper); Limulus (crab).
  • Mollusca – Chaetopleura (Chiton), Loligo (squid), Pila (apple snail), Pinctada (pearl oyster), Sepia (cuttlefish), Loligo (squid), Octopus (devil fish), Aplysia (sea hare), Dentalium.
  • Echinodermata – Asterias (star fish), Echinus (sea urchin), Antedon (sea lily), Cucumaria (sea cucumber), Ophiura (brittle star).



Animalia Invertebrates are the most diverse organisms on earth. Nearly 95% of the animal population falls into the category of invertebrates. According to the International Union for Conservation of Nature 2009 more than 1.3 million invertebrates were identified. Invertebrates make up about 75% of the species on Planet Earth, until their actual number is unknown. The following is the classification of Animalia Invertebrata Sinaumed’s.


The order Ateriodea is also called the starfish, has a star-like shape with five arms, short and blunt spines, has a mouth and anus, very high regenerative power, and locomotors in the form of ambulacral legs. For example: Astrias vulgaris (large starfish).


Order (class) Ophiuroidea Its body is in the form of a pentagonal disc with 5 long arms. The ambulacral lobe apparatus has a mouth but no anus. For example: Ophiothix fragillis (sea star snake).


The Echinoidea class is also called the sea urchin class, the body is round, without arms, has movable spines, a locomotion system with ambulacral legs, some species have poison glands in their spines, and have a complete digestive tract, namely the mouths. anus. For example: Echinocardium cordatum (sea urchin).


The order (class) Holothuroidea has an elliptical body, smooth ossicles, has a mouth and anus, and around the mouth there are movable tentacles (pulled and extended), ambulacral locomotores. For example: Cucumari planci (sea cucumbers).


Order (class) Crinodea has a body shaped like a lily, attached to the seabed, lives in the deep sea and has high regeneration power.

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Protozoa are single-celled animals that live in water, protozoa eat plants and animals, protozoa reproduce by unsexual or vegetative reproduction by dividing and by sexual or generative conjugation. Phylum Protozoa is divided into several classes:

  • Vibrating-haired animal class (cikata)
  • Pseudo-legged animal class (rhizopoda)
  • Class of spores (sporozoa)
  • Class of animals with whips (flogellato)


phylum porifera

Porifera are aquatic animals and live in the sea, their body shape is like a plant attached to a seabed, so they can move around freely, Porifera’s body is like a tube that has many pores (small holes on the sides and has cavities on the inside) Porifera can develop reproduce by generative and vegetative ways. Porifera consists of three classes, here are some of them:

  • Corcorea class: Consists of spicules and lives in shallow seas, for example seghpha SP, charsarina SP
  • Class hexactinelida: Consists of a gritty substance and lives in the deep sea. For example pnerorepa SP
  • Class demospangia: Soft bodies don’t even have a skeleton, for example spongia SP

Phylum Coelentrata

Coelentrata comes from the words coilos (hollow) and entron (intestine). Coelentrata has two forms, namely the passive form which attaches to a base and does not move. Coelentrata consists of 3 classes Anthozoa Class, Hydrozoa Class and Scyphozoan Class. The characteristics are as follows:

  • Multicellular, and radially symmetric (cutting a plane through the center creates identical segments, they have a top and bottom but no sides)
  • It has a tube-like shape
  • Surrounded by tentacles around the mouth. The body layer of the coelenterata consists of the outer tissue (exoderm), inner tissue (endoderm), and the longitudinal and crossed muscle system (mesoglea).
  • Has a cnidoblast, which is an exoderm cell that contains a thorny poison called a nematocyt.
  • Live in fresh water, sea water, in solider (attached to the bottom of the waters) and colonize.
  • Have stinging cells (nematosis)
  • Is a carnivorous animal (eats small invertebrates)
  • Has no organs or organ systems
  • They have no brains, but only nerve impulses that travel through their bodies and can detect signals in their environment.


The word platyhelminthes comes from the Greek words plays (flat) and hemlines (worms). Platyhelminthes berate also has plates. This group of animals has a bilaterally symmetrical body (both sides are the same). Platyhelminthes is divided into three classes, namely Class turbellaria (vibrating hair worms), Class trematodes (sucking worms), and Class cestroda (tape worms). General characteristics include the following:

  • Bilaterally symmetrical body
  • Body shape flat and soft
  • Body unsegmented except Cestoda
  • Acoelomate Triploblastic body layer
  • The excretory tool uses a flame cell
  • Have eyes
  • Hermaphrodite
  • Does not have a means of respiration
  • Digestive system via Gastrovascular
  • The nervous system is a ganglion
  • Free-living in fresh water and damp places


Mollusca (in Latin, molluscus = soft) is a soft-bodied animal. The soft body is protected by a shell, although some are not shelled. These animals are classified as coelomate triploblastic. As the name implies, soft animals have a soft body that is protected by a shell of calcium (lime) material. Molluscs are hermoporite, have a digestive system, respiratory system and excretory system. Molluscs are divided into 4 classes: Class lamilli brancuiata (corals and oysters), Gastropods (snails), Cephalopods (squid) and Amphineura. The characteristics are as follows:

  • The body is bilaterally symmetrical
  • The body wall is triploblastic
  • The short body is protected by the graft which is composed of a calcified substance produced by the mantle substance. Mollusca head structure is growing
  • Digestive apparatus is fully developed Except for cephalopods, the blood circulation is open, the heart consists of a dorsal part surrounded by a pericardium
  • Breathing is done by pulmonum, epidermis, gills or mantle
  • Excretion tools in the form of kidneys Sexual reproduction
  • The nervous system consists of three pairs of nerve nodes (ganglions), namely the cerebral ganglion, visceral ganglion, and pedal ganglion, all three of which are connected by nerve fibers.
  • The genitals are generally separate (dioesus), but some are hermaphrodites. The sexes are separate, fertilization is external


Echinoderms (in Greek, echino = hedgehog, derma = skin) are a group of coelomate tripopoblastic animals which have the characteristic feature of a spiny endoskeleton that penetrates the skin. The phylum echinodermata consists of five classes, namely the starfish class (asteroidal), the sea urchin class (echinoidal), the sea star class (opiuroidal), the sea wax class (crinoidal) and the sea cucumber class (holothuroidae). With the following characteristics:

  • Has three embryonal layers (triploblastic)
  • Bilateral body symmetry in the larval phase and radial in the adult phase
  • There is an anterior and posterior division of the body
  • Euseelomata or coelomate
  • Has no body segments
  • The digestive system is perfect, with some species lacking an anus
  • Does not have a circulatory system
  • The respiratory system is in the form of small gills or papulaedan. There are also those who use ambulacral feet (tube feet), or sea cucumbers
  • Does not have an excretory system
  • The nervous system is formed by ring nerves, radial nerves and mesh nerves
  • Reproduction asexually (regeneration) and sexually.
  • In general, have separate sexes, but some types are hermaphrodite
  • Body support in the form of an internal framework (endoskeleton), in the form of plates and under the skin.


Arthropods or book organisms. Phylum Arthropoda has the largest species, which is 75% of all animals in the world. Arthropoda comes from the Latin: Arthra means segment, book, segment, and Podos means leg which means an animal with jointed, jointed or segmented legs. Arthropod bodies are bilaterally symmetrical and coelomate triploblastic. This phylum has the largest number of species compared to other phyla. Body and legs segmented and bilaterally symmetrical, exoskeleton contains chemicals. Anthropods have blood circulation, but their blood is colorless, their growth takes a long time to undergo metamorphosis (change in shape). Phylum Anthropoda consists of:

  • Insect class (insecta)
  • Spider class (arachoidae)
  • Class crustaceans (erustacea)
  • Centipede class (mynapoda)
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To find out more clearly about what belongs to invertebrate animals, you can read the book Aves Invertebrates – Exploring the Animal World by Genevieve De Becker which presents various examples of invertebrate animals with pictures so they are easier to understand.


Digestive system in Invertebrate Animalia For example in amoeba which is a single-celled animal, all of its life activities occur within the cell itself. Likewise the digestion of food takes place in the cells, it is called the digestion of the senses of the cells. When an amoeba gets food, it immediately forms a pseudo foot which leads to the next food, which is surrounded by pseudo legs, then the food is carried to the protoplasm. In the protoplasm that contains food that produces digestive enzymes. In the food cavity occurs digestion of food. Digested food is in the form of food essence which is absorbed from food residues and excreted from the body.

Digestive system in the hermes group For example in earthworms with a digestive tract consisting of a mouth, esophagus, crop, gizzard, intestine and anus. The front part of the esophagus is slightly enlarged, called the pharynx, which functions to suck food from the mouth and moisten it with mucus. The food of earthworms is in the form of humus which is found in acidic soil, surrounded by an esophagus with three pairs of glands which produce lime which can neutralize the acidic nature of their food.

The digestive system in insect or insect animals, for example grasshoppers, has a cache that functions to temporarily store food. At the bottom of the crop there are salivary glands which drain through the main duct into the oral cavity. From the cache the food enters the gizzard and in the gizzard the food is destroyed, then the food is passed on to the stomach. At the front of the stomach are six pairs of appendixes which function as digestive glands. Undigested food is absorbed in the stomach. Leftovers from the intestine through the pelletum are removed through the sewer or anus.



  • For the Environment:
    • The roles of invertebrates in the environmental area are: Creation of diversity (biodiversity) at the biosphere scale. The number of invertebrates is huge, especially in the Animalia kingdom.
    • Symbiosis with other organisms, for example ready to protect other organisms, such as coral populations, sponges and sea anemones can act as a home or nest for fish and other marine animals.
    • Participate in the food chain. It is not only as consumers that there are species that also act as agents of decomposition. Some members of the annelids such as Lumbricus SP. Is a destroyer in the food chain. While in marine ecosystems, some Echinodermata species can also act as decomposition in water.
    • Ecotourism attractions, such as coral reef ecosystems with various corals, anemones and other invertebrates as protection for invertebrates can be a tourist attraction. In addition, some National Parks can also have an abundance of invertebrate species such as populations of different species of Butterflies in the NP. Bantimurung, which is called the Butterfly kingdom. In Indonesia there are also tourist attractions that have stingless jellyfish.
  • For Health: In the health sector, some members can act as medicine and also act as parasites and cause dangerous diseases for humans, especially members of Phylum Platyhelminthes and Nemathelminthes:
    • Manufacture of bioactive compounds for medicines, can be found in Porifera members in symbiosis with bacteria.
    • Wellness Therapy, such as Leam application and acupuncture with bee stings.
  • For Agriculture: Helps pollinate agricultural crops as bees, butterflies and other insects do. Help maintain, galvanize, ventilate the floor, as earthworms do. As a pest plant destroyer, as occurs in fruit flies, stink bugs, grasshoppers and Mollusca members such as slugs.
  • For Livestock: As a honey producer. Honey bees and several other species of Insecta members that can produce honey. Manufacture of silk materials, where silkworms can be cultivated to be taken from their cocoons as materials made of silk thread. Several species, such as earthworms and several types of insects, are deliberately grown for use as raw materials for Asian medicine, food, cosmetics and animal feed.
  • For Education or Research: The simple body structure makes invertebrates an object of research. For example, fruit flies are often used as objects of genetic research, monitoring of embryonic development with sea urchins as objects, and invertebrates can also be used as a review. In addition, several types of insects are also used as an important source of information in the forensic field.

Thus the definition, characteristics, classification, phylum, digestive system, and benefits of animalia invertebrates in Sinaumed’s’ daily life. Hope it is useful!