There are living examples of oviparous mammals.

Marsupials are mammals that lay eggs and incubate them in a bag called "pouch".

Mammals are ectothermic.

All mammals have their bodies fully covered with hair.

All mammals species possess mammary glands.

Some bird species bear teeth.

Birds are oviparous and reproduce externally.

Birds have their skin covered in feathers and scales.

Birds are vertebrate tetrapods.

Birds are amniotic vertebrates.

Birds are viviparous.

Birds can keep their body temperature constant.

Birds are descendants of the dinosaurs.

Which is number 1?

Which is number 4?

Which is number 5?

Which is number 3?

Which is number 6?

Reptiles' eggs have a tough shell and a membrane called amnion.

Reptiles are amniotic tetrapods.

Reptiles have watertight skin.

Reptiles cannot regulate their internal temperature by means of physiological processes.

Reptiles are viviparous.

Reptiles have their bodies covered in scales.

Reptiles breathe using lungs and through their skin.

Reptiles depend on the aquatic environment in order to reproduce.

They are characterized by being limbless.

Reptiles which possess a bony shell.

Reptiles which are characterized by being limbless.

Reptiles which, in general, do not have teeth.

Reptiles which have no eyelids, so they can't blink.

Reptiles which live partly in aquatic environments and partly on land.

Reptiles which have no external ears.

Which is number 3?

Which is number 2?

Which is number 6?

Which is number 4?

Which is number 1?

Adult amphibians do not depend on the aquatic environment to survive.

During one of their developmental stages, amphibians have a tail.

Young amphibians depend on the aquatic environment to survive.

The skin of amphibians is covered in scales.

Amphibians are ectothermic.

Adult amphibians breathe through their lungs and skin.

Amphibians develop through metamorphosis.

Amphibians that have the ability to regenerate some of their limbs.

Amphibians that are mostly oviparous and reproduce externally.

Amphibians which adults have no limbs.

Cartilaginous fishes have several gills.

Cartilaginous fishes have several gills.

Fishes have the ability to keep their body temperature constant.

Fishes breath through gills.

Bony fishes have the gill covered by an operculum.

Fishes are mostly viviparous.

Fishes reproduce by internal fertilization.

Which type of fish is the one that doesn't have scales?

Which type of fish is the one which gills are covered by an operculum?

Which type of fish is the one that doesn't have a jaw?

Which type of fish is the one that has swim bladder?

Which type of fish is the one which skeleton is totally or partially made u of bony tissue?

Echinoderms need to shed their skeleton to be able to grow.

Echinoderm larvae are bilaterally symmetrical

All echinoderms are marine animals.

Echinoderms have no head.

Echinoderms use tube feet for locomotion or to attach to the substrate.

Echinoderms have no nervous system.

Sexual reproduction in echinoderms is via external fertilization.

In echinoderms, the anus and mouth are the same orifice.

Most adult echinoderms exhibit radial symmetry.

These echinoderms have no arms and are bilaterally symmetrical.

These echinoderms have a central disc and 5 or more highly mobile, articulated arms, with a groove running along the bottom surface of each arm.

These echinoderms have no arms and are radially symmetrical.

These echinoderms have a central disc and 5 or more highly mobile, articulated arms with no groove running along the bottom surface of their arms.

Among these branched-armed echinoderms, there are sessile animals that feed on suspended matter.

Crustaceans are the most widely diverse group of arthropods.

Arthropods need to shed their external skeleton to be able to grow.

Arthropods are, by far, the most widely diverse phylum of the animal kingdom.

All arthropods have antennae.

All arthropods have antennae.

All terrestrial arthropods breathe through their lungs.

The only arthropods bearing wings belong to the class of insects.

All arthropods have appendages to move about and are protected by an exoskeleton.

These arthropods have a distinct head, thorax and abdomen.

Their body plan consists of cephalothorax and abdomen and bear two pairs of antennae.

These arthropods have cephalothorax and abdomen, but no antennae.

These arthropods are characterized by having appendages called "chelicerae".

These arthropods have three pairs of legs.

Their body consists of multiple segments.

These arthropods are mostly marine and breathe through gills.

This is the most widely diverse group of arthropods.

These arthropods have four pairs of legs.

These mollusks lack a distinct head.

Their foot has projections in the form of tentacles.

These mollusks have a muscular foot to creep along the ground and may have an external shell.

It's the class of mollusks with the largest number of species.

These organisms are filter-feeders.

This class of mollusks only live in marine habitats.

These organisms lack radulas.

It's the only class of mollusks which includes terrestrial organisms.

Their eyes are highly developed.

The most common vital strategy of mollusks is parasitism.

Most bivalves are viviparous.

Most mollusks are terrestrial.

Mollusks are soft-bodied organisms, generally surrounded by a protective shell.

Mollusks have a nervous system.

Marine mollusks breathe through the skin and have no respiratory system.

The shell of the mollusks is secreted by the animal itself.

Many annelids have a head equipped with sensory receptors.

Many annelids have a head equipped with sensory receptors.

Annelids are worms formed of multiple segments distributed across their body.

Most annelids are terrestrial.

Some species of annelida breathe through their skin, while others are equipped with external gills.

Almost all annelids are parasitic worms.

Although they may seem equal, the segments in annelids are completely different.

Setae are internal organs typical of annelids.

Parasitic organisms that feed on the blood of vertebrate animals.

Have a differentiated head, setae and parapodia.

These annelids are terrestrial or marine and are characterized by an organ called clitellum.

Feather duster worms and bristle worms belong to this class.

Leeches belong to this class.

Earthworms belong to this class.

The body of nematodes is flattened.

Nematodes lack a nervous system.

Nematodes have internal fertilization.

In many nematode species, the male is much smaller than the female.

Nematodes are oviparous.

All nematodes are parasitic.

Planaria are free-living platyhelminthes.

All platyhelminthes are either marine or parasitic.

There are no platyhelminthes that parasitize humans.

Planaria exclusively reproduce sexually.

Platyhelminthes do not require a respiratory system because oxygen reaches all their cells by diffusion.

Platyhelminthes have two openings, one serving as anus and the other as mouth.

Most platyhelminthes are parasitic, such as tapeworms.

Many cnidaria alternate the medusa and polyp stages in their life cycle.

Corals are cnidaria which have the medusa stage in their life cycle.

All cnidaria are aquatic organisms.

Cnidocytes are the cells of cnidaria involved in food digestion.

The bodies of cnidaria are completely covered by stinging cells.

Cnidaria are carnivores.

Sea anemones are cnidaria that only have the polyp stage in their life cycle.

Polyps and medusas have both nerve cells and sensory receptors.

Sponges are the only animals that do not have a nervous system.

Sponges feed on particles floating freely in the water.

Spicules provide structural support to sponges' bodies.

Choanocytes are cells that create a water flow by rapidly moving their flagellae.

Sponge cells group together to form specialized organs.

Sponges have a digestive system and lack a respiratory system.

The osculum is the cavity through which water enters the sponge.