Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 7 Marine Animals Without a Backbone (II)

2 Arthopods: the armored achievers ( 進步者 )  Phylum Arthopoda  Largest phylum of animal; insects dominate on land but rare in sea  Morphological characters: (1) segmented and bilaterally symmetry, (2) jointed appendages, (3) exoskeleton; protection, support, flexible, attachment  Molt  Limitation in size and growth

Figure 7.27 Crustaceans

4 Subphulum Crustacea Characters: (1) most marine, (2) have gill, (3) chitinous skeleton hardened by calcium carbonate, (4) specialized appendages, (5) two pairs of antennae species with additional undescribed species

Figure 7.28 Copepods -- extremely abundant and important -- filter feeding, parasitism, carnivores

Figure 7.29a Barnacles -- Attach to surface, have cirri ( 蔓足 ) -- filter feeding

Figure 7.30 Amphipods

8 Laterally compressed body < 2 cm in length, planktonic life Common in shore debris Over 5000 species

Figure 7.31 Isopods

10 Isopods About same size as amphipods Flat body, legs similar in size

Fish lice

Krill (euphausiids)

13 Krill (euphausiids) Planktonic shrimp-like crustaceans Size up to 6 cm Distinctive carapace Filter feeder; diatom and planktons Extremely common in polar waters

Decapoda

15 Decapoda  The largest group and largest size of crustaceans  About species  Five pairs of walking legs  Three pairs of maxillipeds( 顎足 ); filtering device  Cephalothorax and abdomen  Shrimp scavenger, lobster nocturnal

Colorful shrimp in tropics

Hermit crab

Coconut crab

Figure 7.36 True crab

20 True crab abdomen is small and typically broad cephalothorax Abdomen is V-shape in male and U- shape in female The largest and most diverse group of decopoda scavengers and predators

21 Biology of Crustaceans Feeding and digestion Nervous system and behavior Reproduction and Life history -- diverse form paralleled by diverse functional features

22 Feeding and digestion  Filter feeding is common for small planktonic crustaceans  Chitinous teeth for grinding and bristle for shifting  Stomach; two-chambered in decapods, connected to digestible glands  Digestion is essentially extracellular  Open circulatory system  Gills

23 Nervous system and behavior  A small, relatively simple brain  Sensory organs are well developed, most have compound eyes  Keen sense of “smell”  A pair of statocyst  The most behaviorally complex invertebrates

24 Reproduction and Life history  Internal fertilization  Mating takes place immediately after the female molts  In amphipods and isopods, eggs are brooded in a chamber  In decapods and others, carry eggs in pleopods  Nauplius( 無節幼蟲 )

Other marine arthopods Horseshore crab

26 Horseshore crab Class Merostomata The “ living fossil ” Live on soft bottom in shallow waters

Sea spiders

28 Sea spiders Class Pycnogonida 4 or more pair of jointed legs A large proboscis with the mouth at the tip Most common in cold waters ; occur throughout the oceans

Insects

30 Insects Class Insecta Have three pairs of legs rare in the sea Live at water ’ s edge; decaying seaweed accumulate at high tide mark scavenger

31 Lophophorates  Unit feeding structure  Characters; (1) suspension feeding, (2) lack of segmentation, (3) bilateral symmetry, (4) have a coelomic cavity and a U-shaped gut

Brozoans

33 Brozoans Phylum Ectoporcta Moss animal, form delicate colonies About 4500 species, almost all marine Zooids ( 個蟲 ) Lophophore is retractable, and ectoprocta

Phoronids

35 Phoronids Phylum Phoronida Worm-like and tube-build animal Have a lophophore, and gut is U- shpaed 20 species, all marine, shallow waters Burrow in sand or attaching tubes

Lamp shells

37 Lamp shells Phylum Brachipod Close to 350 species Have a shell with two parts; dorsal and ventral Have a conspicuous lophophore Found attached to rocks or burrowing in soft sediment

Arrow worm

39 Arrow worm Phylum Chaetognatha About 100 species, all marine Important members of the plankton Almost transparent streamlined Head had eyes, spines and teeth Voracious carnivores

40 Arrow worm Size from few mm to 10 cm Voracious carnivores Motionless in water

Echinoderms: five-way symmetry

42 Echinoderms: five-way symmetry Phylum Echinodermata. Radially symmetry is a secondary development Most have pentamerous radial symmetry

-- Lack head -- no anterior, posterior, dorsal, ventral size

-- Have complete digestive tract and endoskeleton -- Have water vascular system -- endoskeleton; covered by thin layer of ciliated tissue

-- Tube feet are muscular extension of these canal; ampullae ( 壺 ) -- Tube feet often end in a sucker; madreporite ( 篩板 ) -- tube for locomotion and receive stimuli

46 Type of Echinoderms About 7000 species, all marine Benthic animal, widely distributed Sea stars Brittle stars Sea urchins Sea Cucumbers Crinoids

Sea stars

48 Sea stars  Class Asteroidea  Ambulacral groove ( 步帶溝 )  Endoskeleton  Carnivores

-- pincer-like pedicellariae ( 叉棘 )

Brittle stars

51 Brittle stars  Class Ophiuroidae  Snake-like movement of the arms  Tube feet have not suckers, lack anus  Detritivore and carnivore  About 2000 species; widely distributed

Sea urchins

53 Sea urchins Class Echinoidae The endoskeleton form a test Mouth on the bottom and the anus on top Bands of pores Detritivore and carnivore Aristotle ’ s lantern About 1000 species; rocky shore

Sand dollar -- Flattened bodies, short spines, deposit feeder, -- live in soft bottom

Sea Cucumbers

56 Sea cucumber Class Holothuridae Five rows of tube feet are concentrated Oral and aboral surface at the end Tube feet extend from mouth to anus Do not have spines and lack obvious radial symmetry Calcareous spicules; endoskeleton Deposit feeder Secrete toxic substance or evisceration

Crinoids

58 Crinoids  Class Crinoidae  Suspension feeder, about 600 species  Body plan is upside-down brittle star  Tube feet along the arm secrete mucus

Sea lilies Feather star

60 Biology of Echinoderms  Feeding and Digestion  Nervous system and Behavior  Reproduction and Life History -- Radial symmetry associated with sedentary life style

61 Feeding and Digestion  Digestive system is relatively simple  Most sea stars are carnivores; everting stomach, intestine is short or missing, no anus  Gut of sea urchins and sea cucumbers is long and coiled  Coelomic fluid, transport oxygen and nutrients; lack distinct circulatory system  Small, branched projection of the body wall in sea stars and sea urchin  Water is drawn through the anus in sea urchin; respiratory trees

62 Nervous system and Behavior  Coordinates movements in the absence of brain

63 Reproduction and Life history  Sex are separate and external fertilization  Bilateral ciliated larva, metamorphosis inot radial symmetry  Asexual reproduction by separate central disk or body into two pieces  Regeneration

Hemichorodates: a missing link? -- echinoderms and chordate share several feature related to development of embryos -- hemichorodate have basic developmental characteristics of chordates and echinoderms

65 Hemichorodates Phylum Hemichordata Morphology characters: (1) have a nerve cord, (2) openings along the anterior part of the gut About 85 species, most are enteropneusts; acron worm Mucus-secreting proboscis

66 Enteropneusts

67 Chordates without a backbone  Phylum Chordata; protochordates  About species  Characters of (1) a single, hollow nerve cord, (2) have gill (or pharyngeal) slits, (3) a notochord, (4) a post-anal tail, and a ventral heart  No backbone

Tunicates

69 Tunicates Subphylum Urochordatea About 3000 species, all marine Class Ascidiacea Attached to hard surface, the only sessile or attached chordates Body is protected by a tunic Filter feeders; incurrent siphon and excurrent siphon Colonial

70 Tunicates (cont.) Adult posses neither a notochord nor a dorsal nerve cord Tadpole larvae display the fundamental chordate traits; have an eye After metamorphosis, the notochord and tail are reabsorbed

Class Thaliacea; salp

Ascidian

Sea squirt

Class Larvcea, Larvceans

Figure 7.49 Lancelets

77 Lancelets  Subphylum Cephalochordata  Inhabitant of soft bottom, and filter feeder  Using gill to capture and concentrate organic particles