Echinoderms and Chordates: Introduction to the phylum and fishes (pp. 737 – 757,1211-1212) Sharks echinoderms Bony fishes Lancelet Figure 34.1: phylogeny of the Deuterostomes Deuterostomes Protostomes This phylum includes Animals that are not vertebrates: sharks, vertebrates are collectively bony fishes, amphibians, known as invertebrates. Over reptiles (including birds), 95% of the known animal species Deuterostome and mammals are invertebrates, including the development echinoderms, hemichordates, Coelom and xenoturbellids. Triploblasty Bilateral symmetry Echinoderms have a water vascular system. Podia project from the underside of the body. Opening to exterior Tube foot Podia Podia Figure 34.3 Mutable connective tissue Left photo: when first touched or handled, the sea cucumber stiffens its connective tissue. Right photo: after being rubbed vigorously, the body becomes so soft that it flows between the experimenters fingers. Echinoderm diversity: Class Asteroidea (Sea stars) Echinoderm diversity: Class Echinoidea (sea urchins, sand dollars) Sea urchin eating kelp Echinoderm 100 diversity: Class 80 Echinoidea 60 40 To really understand Otter number (% max. count) (% max. count) 20 how cool sea urchins 0 are, I must tell you a (a) Sea otter abundance story about keystone 400 species: 300 2 m 200 100 Grams per 0.25 0 (b) Sea urchin biomass 10 8 sea otters 2 6 4 as keystone species 0.25 m 2 Number per 0 in the N. Pacific 1972 1985 1989 19931997 Year Food chain before killer (c) Total kelp density Food chain after killer whale involvement in chain whales started preying on otters Prey shift in killer whales after sea otters’ numbers have diminished. Echinoderm diversity: Class Holothuroidea (Sea cucumbers) Bizarre defense mechanisms in sea cucumbers: 1. Expel cuverian tubules 2. Eviscerate Tardigrades (water bears) are very small animals that live on moss. They have segmented bodies and unjointed limbs. They grow by molting. Who are they most closely related to? a. arthropods b. platyhelminthes c. annelids d. Mollusks e. nematodes Figure 34.1: The other large Deuterostome phylum, the Chordata Deuterostomes Protostomes This phylum includes Animals that are not vertebrates: sharks, vertebrates are collectively bony fishes, amphibians, known as invertebrates. Over reptiles (including birds), 95% of the known animal species Deuterostome and mammals are invertebrates, including the development echinoderms, hemichordates, Coelom and xenoturbellids. Triploblasty Bilateral symmetry the 4 chordate characteristics Sub-phylum Urochordata: the sea squirts or tunicates They are sessile and often colonial Sea squirts possess pharyngeal slits: Fig 34.5a: But where is the notochord? The dorsal hollow nerve cord? the postanal tail? The larvae has them! Fig. 34.5 Urochordata (tunicates) Water flow Adult Larva Pharyngeal gill slits Dorsal hollow nerve cord Water flow Notochord Muscular, Pharyngeal gill slits post-anal tail Subphylum Cephalochordata: the lancelets Lancelet (Branchiostoma or Amphioxus) Fig. 34.5b Radial symmetry Echinoderms Water vascular system Loss of pharyngeal gill slits Protostomes Outgroups to Chordata Acorn worms Deuterostomes CHORDATA Xenoturbella Loss of pharyngeal gill slits CHORDATA Fig. 34.12: Vertebrates Pharyngeal gill slits Lancelets possess elaborate heads with Tunicates CHORDATA large brains and a cranium, Dorsal hollow nerve cord Notochord VERTEBRATA Muscular, post-anal tail and a vertebral column. Hagfish Lampreys GNATHOSTOMATA Vertebrae, cranium Sharks, rays, skates Ray finned Jaws fishes SARCOPTERYGII Coelacanths Lungs, internal bone (endoskeleton) Lungfish Lobed fins AMPHIBIA TETRAPODA Frogs, toads Salamanders Lactation, fur Limbs AMNIOTA Mammals REPTILIA Lizards, snakes Amniotic egg Scales with hard keratin Turtles Alligators, crocodiles Birds Lampreys (jawless vertebrates) Sea lampreys (Petromyzon marinus) invaded Lake Ontario in 1830 from the sea. When the Welland Canal was built to bypass Niagara falls (1919), they migrated to the rest of the lakes. The catch of lake trout dropped from 15 million pounds at the beginning of the 20th century to ≈ 300,000 in the 60s. Spread of lampreys Radial symmetry Echinoderms Water vascular system Loss of pharyngeal gill slits Protostomes Outgroups to Chordata Acorn worms Deuterostomes CHORDATA Xenoturbella Loss of pharyngeal gill slits CHORDATA Fig. 34.12: Vertebrates Pharyngeal gill slits Lancelets possess elaborate heads with Tunicates CHORDATA large brains and a cranium Dorsal hollow nerve cord Notochord VERTEBRATA Muscular, post-anal tail and a vertebral column. Hagfish Lampreys GNATHOSTOMATA Vertebrae, cranium Sharks, rays, The Gnathostomata are skates vertebrates that possess Ray finned Jaws fishes SARCOPTERYGII jaws. Coelacanths Lungs, internal bone (endoskeleton) Lungfish Lobed fins AMPHIBIA TETRAPODA Frogs, toads Salamanders Lactation, fur Limbs AMNIOTA Mammals REPTILIA Lizards, snakes Amniotic egg Scales with hard keratin Turtles Alligators, crocodiles Birds EVOLUTION OF THE JAW Jawless vertebrate Gill arches Fig. 34.10: The Mouth vertebrate jaw likely Intermediate form (fossil acanthodian fish) evolved from 2 pairs of gill arches Gill (skeletal structures arches that supported the Jaw phayrngeal gill slits) Fossil shark Gill arches Jaw While snorkeling, you come across an animal that is bilaterally symmetrical, has segments, a coelom, does not molt, and whose blastopore forms the mouth. The animal could be a/an: a. Chordate b. annelid c. mollusk d. arthropod e. echinoderm Class Chondrichthyes: Sharks, rays, and chimeras. chimeras rays sharks ≈ 750 species of the cartilagenous fishes. The lateral line system that is used to detect tiny vibrations in the water Neuromasts (tiny pores that open into the lateral line) Sharks have internal fertilization and a diversity of reproductive modes Claspers are paired sperm-transfer organs of male sharks Mating bull sharks viviparous oviparous: Shark eggs Human propaganda….. Bony Vertebrates This clade include 3 taxa (classes) of“fishes” and tetrapods (amphibians, reptiles and mammals). Examples of “fishes”: Hypopocampus erectus Radial symmetry Echinoderms Water vascular system Loss of pharyngeal gill slits Protostomes Outgroups to Chordata Acorn worms Deuterostomes CHORDATA Xenoturbella Loss of pharyngeal gill slits CHORDATA Fig. 34.12: Bony Vertebrates Pharyngeal gill slits Lancelets include 3 taxa of fish, and Tunicates CHORDATA tetrapods (amphibians, Dorsal hollow nerve cord Notochord VERTEBRATA Muscular, post-anal tail mammals and reptiles): Hagfish Lampreys GNATHOSTOMATA Vertebrae, cranium Sharks, rays, skates Ray finned Jaws fishes SARCOPTERYGII Coelacanths Lungs, internal bone (endoskeleton) Lungfish Lobed fins AMPHIBIA TETRAPODA Frogs, toads Salamanders Lactation, fur Limbs AMNIOTA Mammals REPTILIA Lizards, snakes Amniotic egg Scales with hard keratin Turtles Alligators, crocodiles Birds Radial symmetry Echinoderms Water vascular system Loss of pharyngeal gill slits Protostomes Outgroups to Chordata Acorn worms Deuterostomes CHORDATA Xenoturbella Loss of pharyngeal gill slits CHORDATA Fig. 34.12: Bony Vertebrates Pharyngeal gill slits Lancelets include 3 taxa of fish, and Tunicates CHORDATA tetrapods (amphibians, Dorsal hollow nerve cord Notochord VERTEBRATA Muscular, post-anal tail mammals and reptiles): Hagfish Lampreys GNATHOSTOMATA Vertebrae, cranium Sharks, rays, skates Ray finned How would you describe the Jaws fishes SARCOPTERYGII Coelacanths phylogeny of fish (highlightedLungs, internal bone (endoskeleton) Lungfish in blue)? Lobed fins AMPHIBIA TETRAPODA a.Aphyletic Frogs, toads b.Monophyletic Salamanders Lactation, fur Limbs AMNIOTA c.Oligophyletic Mammals REPTILIA Lizards, snakes d.Paraphyletic Amniotic egg e.polyphyletic Scales with hard keratin Turtles Alligators, crocodiles Birds Radial symmetry Echinoderms Water vascular system Loss of pharyngeal gill slits Protostomes Outgroups to Chordata Acorn worms Deuterostomes CHORDATA Xenoturbella Loss of pharyngeal gill slits CHORDATA Fig. 34.12: Bony Vertebrates Pharyngeal gill slits Lancelets include the fish, and Tunicates CHORDATA tetrapods (amphibians, Dorsal hollow nerve cord Notochord VERTEBRATA Muscular, post-anal tail mammals and reptiles): Hagfish Lampreys GNATHOSTOMATA Vertebrae, cranium Sharks, rays, skates Ray finned How would you describe the Jaws fishes SARCOPTERYGII Coelacanths phylogeny of ChondricthyesLungs, internal bone (endoskeleton) Lungfish (sharks)? Lobed fins AMPHIBIA TETRAPODA a.Aphyletic Frogs, toads b.Monophyletic Salamanders Lactation, fur Limbs AMNIOTA c.Oligophyletic Mammals REPTILIA Lizards, snakes d.Paraphyletic Amniotic egg e.polyphyletic Scales with hard keratin Turtles Alligators, crocodiles Birds Radial symmetry Echinoderms Water vascular system Loss of pharyngeal gill slits Protostomes Outgroups to Chordata Acorn worms Deuterostomes CHORDATA Xenoturbella Loss of pharyngeal gill slits CHORDATA Fig. 34.12: Bony Vertebrates Pharyngeal gill slits Lancelets include the fish, and Tunicates CHORDATA tetrapods (amphibians, Dorsal hollow nerve cord Notochord VERTEBRATA Muscular, post-anal tail mammals and reptiles): Hagfish Lampreys GNATHOSTOMATA Vertebrae, cranium Sharks, rays, skates Ray finned Although, fishes are Jaws fishes SARCOPTERYGII Coelacanths paraphyletic,the “fish” are Lungs, internal bone (endoskeleton) Lungfish composed of 6 monophyletic Lobed fins AMPHIBIA TETRAPODA lineages (see 6 blue lines) Frogs, toads Salamanders Lactation, fur Limbs AMNIOTA Mammals REPTILIA Lizards, snakes Amniotic egg Scales with hard