Sponges, the members of the phylum Porifera (/ p ə ˈ r ɪ f ər ə /; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells.. Sponges have unspecialized cells that …

Tardigrades (/ ˈ t ɑːr d ɪ ˌ ɡ r eɪ d z /), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär ("little water bear"). In 1777, the Italian biologist Lazzaro Spallanzani named them Tardigrada (/ t ɑːr …

18/09/2019 · We all know that invertebrates lack backbones, but the differences among the various types of invertebrates go a lot deeper than that. On the following slides, you'll discover the 31 different groups, or phyla, of invertebrates, ranging from amoeba-like placozoans that stick to the sides of fish tanks to marine animals, like octopuses, that can achieve a near-vertebrate …

The presence of pharyngeal slits in hemichordates led to debates of whether this structure was homologous to the slits found in chordates or a result of convergent evolution. With the placement of hemichordates and echinoderms as a sister group to chordates, a new hypothesis has emerged-suggesting that pharyngeal gill slits were present in the deuterostome ancestor . …

The two phyla that have clearly dominated both land and sea since nearly the beginning of animal evolution are the arthropods and chordates, protostomous and deuterostomous coelomates, respectively. A key to arthropod success has been the differentiation of many serially repeated parts, in particular jointed appendages with a rigid exoskeleton , to perform the varied …

02/04/2019 · According to Aztec legend, the first axolotl (pronounced axo-LO-tuhl) was a god who changed his form in order to escape being sacrificed.The sneaky transformation from terrestrial salamander to a fully aquatic form did not save later generations from death. The Aztecs ate axolotls. Back when the animals were common, you could buy them as food in Mexican markets.

A skeleton is the structural frame that supports the body of an animal.There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside the body, and the hydroskeleton, a flexible internal skeleton supported by fluid pressure. Vertebrates are animals with a vertebral …

14/07/2009 · The sea squirts (tunicates) begin their history as tadpole-like chordates, but metamorphose partway through their lives into bottom-dwelling filter feeders that look rather like a bag of seawater ...

Chordates (Tetrapods; semiterrestrial members: Amphibious fish) Roundworms, gastrotrichs, tardigrades, rotifers and some smaller species of arthropods and annelids are microscopic animals that require a film of water to live in, and are therefore considered semi-terrestrial. Flatworms, ribbon worms, velvet worms and annelids all depend on more or less moist habitats.

Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits.Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts.. The earliest organisms that can be …