Phylum Chordata Study Guide PDF

**Phylum Chordata** Chordata - Phlyum 101 **Characteristic features:** 1\. bilaterally symmetrical 2\. triploblastic, coelomata 3\. metamerically segmented 4\. Deuterostomia 5\. They have a **notochord** - (a slender, stiff but flexible rod running along the back) at some stage of their life...

**Phylum Chordata** Chordata - Phlyum 101 **Characteristic features:** 1\. bilaterally symmetrical 2\. triploblastic, coelomata 3\. metamerically segmented 4\. Deuterostomia 5\. They have a **notochord** - (a slender, stiff but flexible rod running along the back) at some stage of their life cycle. In higher Chordata it develops into a vertebral column. 6\. They have a **dorsal hollow nerve** **cord** (Protostomia have a ventral nerve cord). 7\. They have **visceral clefts (pharyngeal slits).** These are perforations on each side of a pharynx which occur in all chordates embryos. They are present in adult stage in primitive chordates, modify into gills in some chordates and are reduced in higher chordates. 8\. They have a **postanal tail** at some stage of their life, which may be reduced or lost in some adult chordates.  9\. They have endoskeleton. 10\. They have a closed circulatory system with a heart (except of Tunicata). 11\. They have a central nervous system (CNS). Chordata -- general characteristic video: [[https://youtu.be/YljHIVUAyig]](https://youtu.be/YljHIVUAyig) **Evolution of Chordata** UWL Website **Classification of Chordata**  Chordate Family Tree \| Carlson Stock Art Chordata characteristics - crash course video: [[https://youtu.be/kgZRZmEc9j4]](https://youtu.be/kgZRZmEc9j4) **Tunicata (Urochordata)**  SOUS LES MERS : Rhopalaea fusca - ascidie bleue à bords orangés They live in marine waters, in **colonies** or as **individuals**. They are attached to the bottom. They have a **barrel shape**, covered with a **cloak** (tunic). Tunic contains **tunicin** / a polysaccharide similar to cellulose.  Untitled Page **Digestive system:** oral siphon (mouth), perforated pharynx (with visceral clefts and **endostyle**), stomach, intestines, anus. The endostyle releases mucus to capture food particles and processes them further to a stomach. They are **filter feeders**. **Breathing system:** **gill basket with visceral clefts -- (gill slits)** (perforated pharynx), atrium (blood (haemolymph) takes oxygen from water), water goes out through atrial siphon **Circulatory system:** **open**, simple heart, no blood vessels **Excretory system:** **nephrocytes**, excretion through anus and atrial siphon **Nervous system:** nerve ganglium on dorsal part, hollow dorsal nerve cord present only **in larval stage** (exception is Appendicularia) **Reproductive system:** hermaphrodits, larval stage, larva **is with notochord and hollow dorsal nerve cord and a postanal tail.** **Classification:** **Class: Ascidiacea** (Ascídie) -- live mostly in colonies, **benthic** (on the bottom of the sea), sessile, filter-feeders, they have notochord, dorsal hollow nerve cord, postanal tail **only in larval stage** **Class: Thaliacea** (Salpy) -- 1 mm- 15 cm small, part of **zooplankton** (**pelagic**), they have a notochord, nerve cord, postanal tail **only in larval stage** **Class: Appendicularia** (Vršovky) \- don´t create colonies, live in seas close to the surface (**pelagic**), part of **plankton**, they have a notochord, dorsal nerve cord and postanal tail **all their life** Tunicata video: [[https://youtu.be/\_rTOQO-M724]](https://youtu.be/_rTOQO-M724) **Subphylum Cephalochordata** **Cephalochordates** (Greek: *kephale*, "head"), because they do not have the braincase, or cranium, of a [vertebrate](https://www.britannica.com/animal/vertebrate), lancelets are often called **acraniates**. also latin A**crania**, any of more than two dozen species belonging to the **subphylum Cephalochordata** of the phylum [Chordata](https://www.britannica.com/animal/chordate). Small, **fishlike marine invertebrates**, they probably are the closest living relatives of the vertebrates. Cephalochordates and vertebrates have a **hollow, dorsal nerve cord, pharyngeal gill slits. a [notochord](https://www.britannica.com/science/notochord) and a post anal tail.**. In most vertebrates, the embryonic notochord is eventually replaced by bony vertebrae or cartilaginous tissue; **among cephalochordates, the notochord is retained into adulthood and is never replaced by vertebrae**. There are about 20 species in two families, each with a single genus. ***Branchiostoma*** (**kopijovec rybkovitý**) (in English **lancelet**) was formerly called ***Amphioxus***, a name that is retained as an informal term. The cephalochordate [fossil record](https://www.britannica.com/science/fossil-record) extends back to about **525 million years** ago during the early part of the **[Cambrian Period](https://www.britannica.com/science/Cambrian-Period).**  **General features** **Size:** Adult ***Branchiostoma*** (lancelets) reach a length of about **six to seven centimetres**. **Importance** Although **edible**, lancelets are never sufficiently abundant to [constitute](https://www.merriam-webster.com/dictionary/constitute) a significant source of food to humans or an important part of the [food chain](https://www.britannica.com/science/food-chain) in nature. Rather, their significance has to do with their place in [**evolution**](https://www.britannica.com/science/evolution-scientific-theory), as **invertebrates transitional to vertebrates** providing clues for the history of human lineage. Lancelets have a structure that illustrates the characteristic features of chordates in simple form. They serve as **a blue print** for studying characteristic features of Chordata. **Digestive system:** Mouth with an **oral hood** and **ciri,** perforated pharynx (with visceral clefts and endostyle), intestines, anus. **Endostyle** -- is an organ in pharynx which produces slime to trap food in perforated pharynx. They are filter feeders. They don´t have a visible stomach. **Breathing system:** The pharynx, with its many gill slits, is surrounded by the [atrium](https://www.britannica.com/science/atrium-heart), a large cavity with a single exit (the **atriopore**) on the lower surface of the body. The atrium protects the gill slits. Oxygen is taken from water. Water is expelled from the body through the atriopore. **Circulatory system:** **Closed**, simple heart **Excretory system:** Excretion is through anus and atriopore. They have **nephridia** similar to Annelida. **Nervous system:** Dorsal hollow nerve cord, **central nervous system** but not visible brain. They have two pairs of peripheral nerves coming our from the dorsal hollow nerve cord in each segment. **Reproductive system:** Lancelet has **separate sexes**, and **asexual reproduction does not occur**. Eggs and sperm are shed directly into the water, where fertilization occurs. **Fertilisation is external**. The early stages of development resemble those of both tunicates and vertebrates. A **larva** is produced that is similar in structure to the adult but is asymmetrical (the gill slits on one side develop first), smaller, and simpler, with fewer gill slits and no atrium. The larvae spend much of their time feeding in the open water but can be found on the bottom. After growing and developing, they **metamorphose** into the adult form and complete their life history in the substrate. **Movement** Lancelets can swim both **forward** and **backward** and can move rapidly through the gravel in which they live. Their behaviour is simple, largely being a matter of locating the proper habitat and escaping from predators. The bodies of lancelets, like those of fishes and other vertebrates, are largely made up of serially repeated units **(segments)** that include blocks of muscles called **[metameres](https://www.britannica.com/science/somite-body-segment) (myotomes)**. They have also fins for movement -- a dorsal, caudal and ventral **odd fins**. 7\. Sub Phylum (Cephalochordata) This segmentation also extends to the nerves that supply the myotomes and to some body cavities, excretory structures, and other parts. **Segmentation is thought to provide more effective body coordination during locomotion.** The segments of vertebrates and cephalochordates are so similar that they were almost certainly present in the common ancestor of the two groups. A distinct "secondary" body cavity **(coelom)**, like that which contains the internal organs in vertebrates and many other animals, **is well developed** and forms a system of cavities and spaces. Like the coelom of hemichordates, echinoderms, and a few other animals, it develops as **outpouchings** in the gut of the embryo. (Deuterostomia)  Body plan of Cephalochordata -- a primary (enteron) and a secondary body cavity (coelom) Difference Between Protostomes and Deuterostomes \| Compare the Difference Between Similar Terms The coelom of echinoderms, and chordates develops as **outpouchings** in the gut of the embryo. (Deuterostomia) **Ecology and habitats** Lancelets are distributed throughout the world along **tropical** and **temperate coasts.** They inhabit **soft bottoms** ranging from **sand** to coarse **shelly sand** or gravel in shallow coastal water. Lancelets lie **buried beneath this substrate**, often with their **mouths protruding above the surface**, allowing them to take in water laden with food. In **China, lancelets are sometimes eaten and even support a small [fishing industry](https://www.britannica.com/technology/commercial-fishing).** http://3.bp.blogspot.com/-EMU8WmcljGc/U7GS7\_Q0njI/AAAAAAAACmc/mamERi84piI/s1600/lamprey.jpg Lancelet video: [[https://youtu.be/XdpXTG9A8\_A]](https://youtu.be/XdpXTG9A8_A) Cephalochordata video: [[https://youtu.be/GbBcqQKfhFI]](https://youtu.be/GbBcqQKfhFI) Internal structure of Cephalochordata :[https://youtu.be/c4r2yf9t6V0] Spodná časť formulára