Penutup tubuh ikan (kulit, sisik, jari-jari sirip, tulang kepala,warna, kelenjar beracun)

Sistem integumen
Penutup tubuh ikan (kulit,
sisik, jari-jari sirip, tulang
kepala,warna, kelenjar
beracun)

Fungsi kulit tubuh ikan
• Pertahanan pertama terhadap
penyakit
• Perlindungan terhadap kondisi
sekeliling
• Alat bantu pernafasan
• Tempat kelenjar beracun
• Sumber pewarnaan
• Sumber cahaya
• Tempat lendir dan bau yang khas

epidermis
• Stratum germinativum

–

–
–
–
–

Cuboidal
Mitotic Division
Migrate Distally
Diferentiate
Sloughed of

(aktif membelah untuk
mengganti sel yang terlepas dan
untuk pertumbuhan)
• Synthesis of keratin
– Water insoluble protein that
flls cells
– Stratum corneum of
Vertebrates
Selalu basah karena sel-sel

kelenjar di seluruh permukaan
tubuh

Dermis
–

–

–

Proximal Migration and
diferentiation of of
collagen fbers and other
structures
Untuk ikan bersisik
berperan dalam
pembentukan sisik)
Two layers
•
•

–

Stratum laxum
(spongiosum)
Stratum compactum

Blood vessels, nerves,
pigment cells
– “Ancient
and
persistent
Endotherms
– bases
of hairpotential to form bone”
and feathers + erector

Fish
No dead cells like mammals, cells
alive, no keratin production in cells

except for horny teeth of lampreys
and nuptial tubercles

Glands
1. Unicellular - abundant
mucous glands in epidermis.
• maintains stable internal
environment
• protects form bacteria,
ectoparasites
• reduces drag when swimming
Some glands (granular) secrete
pheromones when fish injured,
triggers reaction in nearby fish

2. Multicellular glands growing down into dermis are uncommon
• large slime glands in hagfish
• poison glands (spines)
• light generating glands
Photoblepharon

Flashlight fish – contains
symbiotic bacteria, shutter
mechanism
Angler fish

Flatfish camouflage
operates through visual
system (blinded fish go
dark) but still uses
sympathetic ns & MSH to
alter chromatophore units

Bony scales
Same as bone in mammals, osteocytes, lacunae,
canaliculi, hydroxyapatite mineral, teleosts have
acellular bone.

Develop in exactly the same way as teeth, original dermal
cells of papilla are neural crest.

Next, epidermal cells induced to AMELOBLASTS to form enamel organ
= enamel.
Next ameloblasts induce odontoblasts in dermal cells underneath

Enamel, hardest tissue in body, 96%
hydroxyapatite. If deposited in waves
gives lamellar appearance

Shark has vascular cavity,
but same materials.
Very hard capping material

Isolated remnants of the early
jawless fishes which first evolved –
cosmoid plates – dermal armour.

lendir
• Gel protein (muein), tersentuh air menjadi
lendir, tebal pada ikan tidak bersisik

• Fungsi lendir:
• a. mengurangi gesekan dengan air, ikan bisa
•
•
•
•
•

berenang cepat
B. permeabel, mencegah keluarmasuknya air melalui
kulit
C. mencegah infeksi
D. penutup luka
E. mencegah kekeringan kulit
F. bahan pembuat sarang (ikan paru-paru saat tidur
musim panas, ikan sepat jawa dan sepat siam
membuat sarang dari lendir saat memijah)

lendir

• Fish are aquatic
– Conservation of structure and function among
the diferent fsh groups.
– Bony scales
• Characterize the skin of most fshes
• Substances (tissues) that contribute to bony scales
– Bone
– Dentine
– Enamel

Function of bony scales
• Protection from parasites, other predators
• Positioning:
– Slide one atop the next
– Allow for the distortion of body

• Hydrodynamic function to reduce drag
• Feeding

• Cellular Bone

– Extra-cellular matrix of collagen fbers
– Embedded in polysaccharide ground substance
– Matrix laid down by osteoblasts
• Diferentiate from mesenchyme cells of the dermis

– Calcium phosphate crystals (hydroxyapatite) bind to
fbers
– During osteogenesis
• Osteoblasts mature and become entrapped in matrix –
osteocytes
• Osteocytes are located in lacunae
– Small cavities interconnected by canals (canaliculi)
– Cell processes are extended through these canals

• Bone of fsh scales
– “dermal bone” (cf. “cellular bone”)

Bony scales
• Bone is deposited by osteocytes on
the periphery of a developing scale

• Osteocytes move centrifugally away
from center of scale
• No bone cells or processes are left
behind
• Then dentine and enamel layers can
be added to the surface of the bone
for increased hardness of scale

Dentine and Enamel
•
•

Mesenchymal aggregation (papilla) beneath basement
membrane
Basal cells above the papillae respond and diferentiate into
ameloblasts
– Ameloblasts – collectively called the enamel organ
– Secrete enamel
– Retreat

•

Underlying dermal cells diferentiate into odontoblasts
– secrete dentine
– Retreat in direction opposite of ameloblasts
– Leave long cytoplasmic processes – dentine tubules

Types of Bony Scales
• Cosmoid plates and
scales
– Ostracoderms
– Cosmine – “dentine”

• Ganoid plates and scales
– Actinopterygian fshes
– Bichirs (Polypterus),
Garpikes

Types of Bony Scales
• Modern
– Cycloid and Ctenoid
– Most teleosts

Dermal Scales

re 8.7: Cycloid, ctenoid, placoid, and ganoid scales of modern fsh.

Figure 8.8:
Derivatives of
primitive dermal
bone.

Dermal Scales

Figure 8.9

• Ctenoid scales
– Growth rings or annuli

• Fish have no epidermal
scales
– Scales are dermal

Sisik ikan
• Cycloid dan ctenoid: bentuk sangat tipis,
transparant, tidak mengandung dentin
dan enamel, terdapat pada ikan bertulang
sejati. Cycloid terdapat pada ikan berjari
sirip lemah (Malacopterygii). Ctenoid
terdapat pada ikan berjari sirip keras
(Acanthopterygii)
• Cosmoid: pada fosil ikan, komponennya
virodentin, cosmin, isopedin (bahan
tulang) dan pembuluh darah kecil

Sisik ikan
• Ganoid: pada ikan Actinopterygii,
lapisan luar mengandung garam
organik (ganoine)
• Placoid: pada ikan Chondrichthyes,
seperti duri, bahan sama seperti gigi.
Lapisan terluar dilapisi enamel yang
membungkus dentin. Didalam dentin
ada canaculi, ada pembuluh darah
dan ujung syaraf dermis

Sisik placoid

placoid
•
• Placoid scales – paleozoic
sharks, elasmobranchs
– Also called dermal denticles
– Spinous process
• From dermis

– Dentine, surrounding a
vascular pulp cavity and
capped by enamel
– Become teeth at jaws

Sisik cosmoid

Sisik ganoid

Sisik ikan cycloid dan
ctenoid

Letak sisik ikan
• Menyeluruh (belakang operculum sampai sirip
caudal): ikan betok/betik, ikan gabus
• Tidak merata: polyodon (dibawah operculum),
tongkol (bagian depan dorsal dibelakang
kepala), ikan mas (disekitar lateral line)
• Tidak bersisik: ikan lele
• Setengah bagian sisik menempel pada
kantong di dermis dengan susunan seperti
genting (anterior: tidak berwarna, posterior:
berpigmen)

Sisik ikan
• Selama pertumbuhan ikan, sisiknya
bertambah (ukuran) tidak dalam jumlahnya
• Ruptur sisik: bisa diganti sisik baru
• Garis lingkaran (circulus) selalu bertambah
selama hidup ikan
• Circulus yang berdempetan = annulus,
annuli (banyak), untuk menghitung umur
ikan
• Sisik lateral line tidak bisa digunakan untuk
menghitung umur ikan

Warna ikan
• Intensitas warna ikan berkurang saat ikan
mati
• Warna ikan bisa lebih indah dibanding warna
burung atau kupu-kupu
• Tidak semua ikan berwarna cerah, terkadang
berwarna coklat, abu-abu, hitam yang
merata di seluruh tubuh
• Warna ikan merefeksikan tempat hidupnya
• Ikan dasar: warna pucat di bagian perut dan
gelap di bagian punggung

Warna ikan
• Ikan laut memiliki 3 warna dasar, ikan di
permukaan laut bewarna keperakan,
kemerahan di perairan agak dalam, dan
ungu kehitaman atau hitam di laut dalam
• Ikan yang hidup di karang memiliki totol
warna sesuai lingkungannya (mimieri)
• Ikan bisa berkamufase warna karena
adanya predator, disebabkan stimuli mata
(perubahan secara cepat) dan hormon
(perubahan secara lambat)

warna ikan

Sel warna ikan
• Iridocyte (leucophore dan
guanophore), tersusun dari guanin,
merefeksi warna di luar tubuh = sel
kaca
• Chromatophore, ada di dermis, jika
warna mengumpul ikan berwarna
pucat, jika menyebar, warna menjadi
jelas, ikan berwarna cerah

• Chromatophore dasar ada 4:
erythrophore (merah oranye),
xanthophore (kuning),
melanophore (hitam), guanophore
(putih keperakan karena sel
iridocyte)

Body Coloration
1) source of color
a) pigment color - chromatophores for yellows,
reds, oranges, browns, & blacks
b) structural color - iridophores (reflection) &
light refraction for blues, silvers, & rainbows

2) patterns (pp. 152-153)
a) countershading
1) dark blue or black dorsally, white or silvery
ventrally
2) results in blue water "camouflage“
3) observed most frequently in pelagic cruisers

b) camouflage
1) matching the background coloration
2) usually involves having irregular dark
blotches and spots
3) typically seen in benthic fishes, especially
benthic ambush predators (e.g., frogfishes,
gobies, & many scorpionfishes)
4) some fishes (e.g., flatfishes) may exhibit
rapid color changes in response to different
backgrounds

b) camouflage
5) matching downwelling light

Hatchet fish

Cookie cutter shark

c) disruptive coloration
1) color pattern breaks up the silhouette
of the fish
2) may involve dark bars across the eye
and tail region
3) seen in many demersal fishes such as
butterflyfishes

d) bars and stripes
1) bars are vertical (e.g., manini)
2) stripes are horizontal (e.g., ta'ape)
3) seen frequently in schooling demersal
fishes
4) may confuse potential predators by
making it difficult to select individual
prey from the school

e) misdirection
1) false eye spots, etc.
2) observed in many demersal butterflyfishes

f) advertising coloration
1) bright, obvious color patterns
2) possible functions
a) advertising a cleaning station
cleaner wrasses)
b) advertising a warning (e.g., nohu)
c) advertising for mates (e.g., male
parrotfishes)

Hawaiian cleaner
wrasse

Nohu

(e.g.,

g) mimicry
1) imitating other creatures
2) seen in a few demersal and benthic fishes
3) examples
a) blenny (Aspidontus taeniatus) mimics
cleaner wrasses

b) shortnose wrasse mimics Potter's angel
which sports a defensive spine

g) mimicry
4) leafy sea dragon (Australia)

h) uniform red coloration
1) most often observed in deep-dwelling or
night active demersal fishes
2) examples include opakapaka, oweoweo,
menpachi, & squirrelfishes

i)

noctural versus diurnal color changes

j)

male versus female color differences

k)

juvenile versus adult color differences

Bluehead wrasse
Stoplight parrotfish

Dragon wrasse

Organ bercahaya

Asal cahaya pada ikan
• Bakteri yang bersimbiose dengan ikan,
terdapat pada kantong kelenjar epidermis.
Contoh ikan famili Monocentridae, Gadidae,
Leognathidae, Serranidae, Macroridae
• Pemantulan cahaya diatur oleh jaringan yang
berfungsi sebagai lensa. Bagian berlawanan
lensa banyak pigmen yang berfungsi sebagai
pemantul. Pemancaran cahaya yang
dikeluarkan bakteri diatur oleh kontraksi
pigmen yang berfungsi sebagai iris mata

Asal cahaya pada ikan
• Dikeluarkan langsung oleh sel kulit
ikan = photophore/ photocyte
• Elasmobranch: Etmopterus,
Benthobatis, Spinax
• Teleost: Batrachoididae, Stomiatidae

Kelenjar beracun

• Potamotrygon, ikan air tawar di
Amerika, memiliki racun seperti
racun ular
• Ikan lepu tembaga (Synanoeja sp):
racunnya pada lapisan kulit penutup
jari-jari keras D dan V
• Ikan beronang (Sigamus spp),
kelenjar beracun pada jari-jari sirip
keras D dan V
• Ikan pari : racunnya pada ekor
• Ikan lele lokal jawa, kelenjar
racunnya pada jari-jari keras D dan P